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 //===- ASTContext.h - Context to hold long-lived AST nodes ------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 /// \file
 /// Defines the clang::ASTContext interface.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_CLANG_AST_ASTCONTEXT_H
 #define LLVM_CLANG_AST_ASTCONTEXT_H
 
 #include "clang/AST/ASTFwd.h"
 #include "clang/AST/CanonicalType.h"
 #include "clang/AST/CommentCommandTraits.h"
 #include "clang/AST/ComparisonCategories.h"
 #include "clang/AST/Decl.h"
 #include "clang/AST/DeclarationName.h"
 #include "clang/AST/ExternalASTSource.h"
 #include "clang/AST/PrettyPrinter.h"
 #include "clang/AST/RawCommentList.h"
 #include "clang/AST/SYCLKernelInfo.h"
 #include "clang/AST/TemplateName.h"
 #include "clang/Basic/LLVM.h"
 #include "clang/Basic/PartialDiagnostic.h"
 #include "clang/Basic/SourceLocation.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/FoldingSet.h"
 #include "llvm/ADT/IntrusiveRefCntPtr.h"
 #include "llvm/ADT/MapVector.h"
 #include "llvm/ADT/PointerIntPair.h"
 #include "llvm/ADT/PointerUnion.h"
 #include "llvm/ADT/SetVector.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/StringSet.h"
 #include "llvm/ADT/TinyPtrVector.h"
 #include "llvm/Support/TypeSize.h"
 #include <optional>
 
 namespace llvm {
 
 class APFixedPoint;
 class FixedPointSemantics;
 struct fltSemantics;
 template <typename T, unsigned N> class SmallPtrSet;
 
 } // namespace llvm
 
 namespace clang {
 
 class APValue;
 class ASTMutationListener;
 class ASTRecordLayout;
 class AtomicExpr;
 class BlockExpr;
 struct BlockVarCopyInit;
 class BuiltinTemplateDecl;
 class CharUnits;
 class ConceptDecl;
 class CXXABI;
 class CXXConstructorDecl;
 class CXXMethodDecl;
 class CXXRecordDecl;
 class DiagnosticsEngine;
 class DynTypedNodeList;
 class Expr;
 enum class FloatModeKind;
 class GlobalDecl;
 class IdentifierTable;
 class LangOptions;
 class MangleContext;
 class MangleNumberingContext;
 class MemberSpecializationInfo;
 class Module;
 struct MSGuidDeclParts;
 class NestedNameSpecifier;
 class NoSanitizeList;
 class ObjCCategoryDecl;
 class ObjCCategoryImplDecl;
 class ObjCContainerDecl;
 class ObjCImplDecl;
 class ObjCImplementationDecl;
 class ObjCInterfaceDecl;
 class ObjCIvarDecl;
 class ObjCMethodDecl;
 class ObjCPropertyDecl;
 class ObjCPropertyImplDecl;
 class ObjCProtocolDecl;
 class ObjCTypeParamDecl;
 class OMPTraitInfo;
 class ParentMapContext;
 struct ParsedTargetAttr;
 class Preprocessor;
 class ProfileList;
 class StoredDeclsMap;
 class TargetAttr;
 class TargetInfo;
 class TemplateDecl;
 class TemplateParameterList;
 class TemplateTemplateParmDecl;
 class TemplateTypeParmDecl;
 class TypeConstraint;
 class UnresolvedSetIterator;
 class UsingShadowDecl;
 class VarTemplateDecl;
 class VTableContextBase;
 class XRayFunctionFilter;
 
 /// A simple array of base specifiers.
 typedef SmallVector<CXXBaseSpecifier *, 4> CXXCastPath;
 
 namespace Builtin {
 
 class Context;
 
 } // namespace Builtin
 
 enum BuiltinTemplateKind : int;
 enum OpenCLTypeKind : uint8_t;
 
 namespace comments {
 
 class FullComment;
 
 } // namespace comments
 
 namespace interp {
 
 class Context;
 
 } // namespace interp
 
 namespace serialization {
 template <class> class AbstractTypeReader;
 } // namespace serialization
 
 enum class AlignRequirementKind {
   /// The alignment was not explicit in code.
   None,
 
   /// The alignment comes from an alignment attribute on a typedef.
   RequiredByTypedef,
 
   /// The alignment comes from an alignment attribute on a record type.
   RequiredByRecord,
 
   /// The alignment comes from an alignment attribute on a enum type.
   RequiredByEnum,
 };
 
 struct TypeInfo {
   uint64_t Width = 0;
   unsigned Align = 0;
   AlignRequirementKind AlignRequirement;
 
   TypeInfo() : AlignRequirement(AlignRequirementKind::None) {}
   TypeInfo(uint64_t Width, unsigned Align,
            AlignRequirementKind AlignRequirement)
       : Width(Width), Align(Align), AlignRequirement(AlignRequirement) {}
   bool isAlignRequired() {
     return AlignRequirement != AlignRequirementKind::None;
   }
 };
 
 struct TypeInfoChars {
   CharUnits Width;
   CharUnits Align;
   AlignRequirementKind AlignRequirement;
 
   TypeInfoChars() : AlignRequirement(AlignRequirementKind::None) {}
   TypeInfoChars(CharUnits Width, CharUnits Align,
                 AlignRequirementKind AlignRequirement)
       : Width(Width), Align(Align), AlignRequirement(AlignRequirement) {}
   bool isAlignRequired() {
     return AlignRequirement != AlignRequirementKind::None;
   }
 };
 
 /// Holds long-lived AST nodes (such as types and decls) that can be
 /// referred to throughout the semantic analysis of a file.
 class ASTContext : public RefCountedBase<ASTContext> {
   friend class NestedNameSpecifier;
 
   mutable SmallVector<Type *, 0> Types;
   mutable llvm::FoldingSet<ExtQuals> ExtQualNodes;
   mutable llvm::FoldingSet<ComplexType> ComplexTypes;
   mutable llvm::FoldingSet<PointerType> PointerTypes{GeneralTypesLog2InitSize};
   mutable llvm::FoldingSet<AdjustedType> AdjustedTypes;
   mutable llvm::FoldingSet<BlockPointerType> BlockPointerTypes;
   mutable llvm::FoldingSet<LValueReferenceType> LValueReferenceTypes;
   mutable llvm::FoldingSet<RValueReferenceType> RValueReferenceTypes;
   mutable llvm::FoldingSet<MemberPointerType> MemberPointerTypes;
   mutable llvm::ContextualFoldingSet<ConstantArrayType, ASTContext &>
       ConstantArrayTypes;
   mutable llvm::FoldingSet<IncompleteArrayType> IncompleteArrayTypes;
   mutable std::vector<VariableArrayType*> VariableArrayTypes;
   mutable llvm::ContextualFoldingSet<DependentSizedArrayType, ASTContext &>
       DependentSizedArrayTypes;
   mutable llvm::ContextualFoldingSet<DependentSizedExtVectorType, ASTContext &>
       DependentSizedExtVectorTypes;
   mutable llvm::ContextualFoldingSet<DependentAddressSpaceType, ASTContext &>
       DependentAddressSpaceTypes;
   mutable llvm::FoldingSet<VectorType> VectorTypes;
   mutable llvm::ContextualFoldingSet<DependentVectorType, ASTContext &>
       DependentVectorTypes;
   mutable llvm::FoldingSet<ConstantMatrixType> MatrixTypes;
   mutable llvm::ContextualFoldingSet<DependentSizedMatrixType, ASTContext &>
       DependentSizedMatrixTypes;
   mutable llvm::FoldingSet<FunctionNoProtoType> FunctionNoProtoTypes;
   mutable llvm::ContextualFoldingSet<FunctionProtoType, ASTContext&>
     FunctionProtoTypes;
   mutable llvm::ContextualFoldingSet<DependentTypeOfExprType, ASTContext &>
       DependentTypeOfExprTypes;
   mutable llvm::ContextualFoldingSet<DependentDecltypeType, ASTContext &>
       DependentDecltypeTypes;
 
   mutable llvm::FoldingSet<PackIndexingType> DependentPackIndexingTypes;
 
   mutable llvm::FoldingSet<TemplateTypeParmType> TemplateTypeParmTypes;
   mutable llvm::FoldingSet<ObjCTypeParamType> ObjCTypeParamTypes;
   mutable llvm::FoldingSet<SubstTemplateTypeParmType>
     SubstTemplateTypeParmTypes;
   mutable llvm::FoldingSet<SubstTemplateTypeParmPackType>
     SubstTemplateTypeParmPackTypes;
   mutable llvm::ContextualFoldingSet<TemplateSpecializationType, ASTContext&>
     TemplateSpecializationTypes;
   mutable llvm::FoldingSet<ParenType> ParenTypes{GeneralTypesLog2InitSize};
   mutable llvm::FoldingSet<UsingType> UsingTypes;
   mutable llvm::FoldingSet<TypedefType> TypedefTypes;
   mutable llvm::FoldingSet<ElaboratedType> ElaboratedTypes{
       GeneralTypesLog2InitSize};
   mutable llvm::FoldingSet<DependentNameType> DependentNameTypes;
   mutable llvm::ContextualFoldingSet<DependentTemplateSpecializationType,
                                      ASTContext&>
     DependentTemplateSpecializationTypes;
   mutable llvm::FoldingSet<PackExpansionType> PackExpansionTypes;
   mutable llvm::FoldingSet<ObjCObjectTypeImpl> ObjCObjectTypes;
   mutable llvm::FoldingSet<ObjCObjectPointerType> ObjCObjectPointerTypes;
   mutable llvm::FoldingSet<DependentUnaryTransformType>
     DependentUnaryTransformTypes;
   // An AutoType can have a dependency on another AutoType via its template
   // arguments. Since both dependent and dependency are on the same set,
   // we can end up in an infinite recursion when looking for a node if we used
   // a `FoldingSet`, since both could end up in the same bucket.
   mutable llvm::DenseMap<llvm::FoldingSetNodeID, AutoType *> AutoTypes;
   mutable llvm::FoldingSet<DeducedTemplateSpecializationType>
     DeducedTemplateSpecializationTypes;
   mutable llvm::FoldingSet<AtomicType> AtomicTypes;
   mutable llvm::FoldingSet<AttributedType> AttributedTypes;
   mutable llvm::FoldingSet<PipeType> PipeTypes;
   mutable llvm::FoldingSet<BitIntType> BitIntTypes;
   mutable llvm::ContextualFoldingSet<DependentBitIntType, ASTContext &>
       DependentBitIntTypes;
   mutable llvm::FoldingSet<BTFTagAttributedType> BTFTagAttributedTypes;
   llvm::FoldingSet<HLSLAttributedResourceType> HLSLAttributedResourceTypes;
 
   mutable llvm::FoldingSet<CountAttributedType> CountAttributedTypes;
 
   mutable llvm::FoldingSet<QualifiedTemplateName> QualifiedTemplateNames;
   mutable llvm::FoldingSet<DependentTemplateName> DependentTemplateNames;
   mutable llvm::FoldingSet<SubstTemplateTemplateParmStorage>
     SubstTemplateTemplateParms;
   mutable llvm::ContextualFoldingSet<SubstTemplateTemplateParmPackStorage,
                                      ASTContext&>
     SubstTemplateTemplateParmPacks;
   mutable llvm::ContextualFoldingSet<DeducedTemplateStorage, ASTContext &>
       DeducedTemplates;
 
   mutable llvm::ContextualFoldingSet<ArrayParameterType, ASTContext &>
       ArrayParameterTypes;
 
   /// The set of nested name specifiers.
   ///
   /// This set is managed by the NestedNameSpecifier class.
   mutable llvm::FoldingSet<NestedNameSpecifier> NestedNameSpecifiers;
   mutable NestedNameSpecifier *GlobalNestedNameSpecifier = nullptr;
 
   /// A cache mapping from RecordDecls to ASTRecordLayouts.
   ///
   /// This is lazily created.  This is intentionally not serialized.
   mutable llvm::DenseMap<const RecordDecl*, const ASTRecordLayout*>
     ASTRecordLayouts;
   mutable llvm::DenseMap<const ObjCContainerDecl*, const ASTRecordLayout*>
     ObjCLayouts;
 
   /// A cache from types to size and alignment information.
   using TypeInfoMap = llvm::DenseMap<const Type *, struct TypeInfo>;
   mutable TypeInfoMap MemoizedTypeInfo;
 
   /// A cache from types to unadjusted alignment information. Only ARM and
   /// AArch64 targets need this information, keeping it separate prevents
   /// imposing overhead on TypeInfo size.
   using UnadjustedAlignMap = llvm::DenseMap<const Type *, unsigned>;
   mutable UnadjustedAlignMap MemoizedUnadjustedAlign;
 
   /// A cache mapping from CXXRecordDecls to key functions.
   llvm::DenseMap<const CXXRecordDecl*, LazyDeclPtr> KeyFunctions;
 
   /// Mapping from ObjCContainers to their ObjCImplementations.
   llvm::DenseMap<ObjCContainerDecl*, ObjCImplDecl*> ObjCImpls;
 
   /// Mapping from ObjCMethod to its duplicate declaration in the same
   /// interface.
   llvm::DenseMap<const ObjCMethodDecl*,const ObjCMethodDecl*> ObjCMethodRedecls;
 
   /// Mapping from __block VarDecls to BlockVarCopyInit.
   llvm::DenseMap<const VarDecl *, BlockVarCopyInit> BlockVarCopyInits;
 
   /// Mapping from GUIDs to the corresponding MSGuidDecl.
   mutable llvm::FoldingSet<MSGuidDecl> MSGuidDecls;
 
   /// Mapping from APValues to the corresponding UnnamedGlobalConstantDecl.
   mutable llvm::FoldingSet<UnnamedGlobalConstantDecl>
       UnnamedGlobalConstantDecls;
 
   /// Mapping from APValues to the corresponding TemplateParamObjects.
   mutable llvm::FoldingSet<TemplateParamObjectDecl> TemplateParamObjectDecls;
 
   /// A cache mapping a string value to a StringLiteral object with the same
   /// value.
   ///
   /// This is lazily created.  This is intentionally not serialized.
   mutable llvm::StringMap<StringLiteral *> StringLiteralCache;
 
   /// The next string literal "version" to allocate during constant evaluation.
   /// This is used to distinguish between repeated evaluations of the same
   /// string literal.
   ///
   /// We don't need to serialize this because constants get re-evaluated in the
   /// current file before they are compared locally.
   unsigned NextStringLiteralVersion = 0;
 
   /// MD5 hash of CUID. It is calculated when first used and cached by this
   /// data member.
   mutable std::string CUIDHash;
 
   /// Representation of a "canonical" template template parameter that
   /// is used in canonical template names.
   class CanonicalTemplateTemplateParm : public llvm::FoldingSetNode {
     TemplateTemplateParmDecl *Parm;
 
   public:
     CanonicalTemplateTemplateParm(TemplateTemplateParmDecl *Parm)
         : Parm(Parm) {}
 
     TemplateTemplateParmDecl *getParam() const { return Parm; }
 
     void Profile(llvm::FoldingSetNodeID &ID, const ASTContext &C) {
       Profile(ID, C, Parm);
     }
 
     static void Profile(llvm::FoldingSetNodeID &ID,
                         const ASTContext &C,
                         TemplateTemplateParmDecl *Parm);
   };
   mutable llvm::ContextualFoldingSet<CanonicalTemplateTemplateParm,
                                      const ASTContext&>
     CanonTemplateTemplateParms;
 
   TemplateTemplateParmDecl *
     getCanonicalTemplateTemplateParmDecl(TemplateTemplateParmDecl *TTP) const;
 
   /// The typedef for the __int128_t type.
   mutable TypedefDecl *Int128Decl = nullptr;
 
   /// The typedef for the __uint128_t type.
   mutable TypedefDecl *UInt128Decl = nullptr;
 
   /// The typedef for the target specific predefined
   /// __builtin_va_list type.
   mutable TypedefDecl *BuiltinVaListDecl = nullptr;
 
   /// The typedef for the predefined \c __builtin_ms_va_list type.
   mutable TypedefDecl *BuiltinMSVaListDecl = nullptr;
 
   /// The typedef for the predefined \c id type.
   mutable TypedefDecl *ObjCIdDecl = nullptr;
 
   /// The typedef for the predefined \c SEL type.
   mutable TypedefDecl *ObjCSelDecl = nullptr;
 
   /// The typedef for the predefined \c Class type.
   mutable TypedefDecl *ObjCClassDecl = nullptr;
 
   /// The typedef for the predefined \c Protocol class in Objective-C.
   mutable ObjCInterfaceDecl *ObjCProtocolClassDecl = nullptr;
 
   /// The typedef for the predefined 'BOOL' type.
   mutable TypedefDecl *BOOLDecl = nullptr;
 
   // Typedefs which may be provided defining the structure of Objective-C
   // pseudo-builtins
   QualType ObjCIdRedefinitionType;
   QualType ObjCClassRedefinitionType;
   QualType ObjCSelRedefinitionType;
 
   /// The identifier 'bool'.
   mutable IdentifierInfo *BoolName = nullptr;
 
   /// The identifier 'NSObject'.
   mutable IdentifierInfo *NSObjectName = nullptr;
 
   /// The identifier 'NSCopying'.
   IdentifierInfo *NSCopyingName = nullptr;
 
   /// The identifier '__make_integer_seq'.
   mutable IdentifierInfo *MakeIntegerSeqName = nullptr;
 
   /// The identifier '__type_pack_element'.
   mutable IdentifierInfo *TypePackElementName = nullptr;
 
   /// The identifier '__builtin_common_type'.
   mutable IdentifierInfo *BuiltinCommonTypeName = nullptr;
 
   QualType ObjCConstantStringType;
   mutable RecordDecl *CFConstantStringTagDecl = nullptr;
   mutable TypedefDecl *CFConstantStringTypeDecl = nullptr;
 
   mutable QualType ObjCSuperType;
 
   QualType ObjCNSStringType;
 
   /// The typedef declaration for the Objective-C "instancetype" type.
   TypedefDecl *ObjCInstanceTypeDecl = nullptr;
 
   /// The type for the C FILE type.
   TypeDecl *FILEDecl = nullptr;
 
   /// The type for the C jmp_buf type.
   TypeDecl *jmp_bufDecl = nullptr;
 
   /// The type for the C sigjmp_buf type.
   TypeDecl *sigjmp_bufDecl = nullptr;
 
   /// The type for the C ucontext_t type.
   TypeDecl *ucontext_tDecl = nullptr;
 
   /// Type for the Block descriptor for Blocks CodeGen.
   ///
   /// Since this is only used for generation of debug info, it is not
   /// serialized.
   mutable RecordDecl *BlockDescriptorType = nullptr;
 
   /// Type for the Block descriptor for Blocks CodeGen.
   ///
   /// Since this is only used for generation of debug info, it is not
   /// serialized.
   mutable RecordDecl *BlockDescriptorExtendedType = nullptr;
 
   /// Declaration for the CUDA cudaConfigureCall function.
   FunctionDecl *cudaConfigureCallDecl = nullptr;
 
   /// Keeps track of all declaration attributes.
   ///
   /// Since so few decls have attrs, we keep them in a hash map instead of
   /// wasting space in the Decl class.
   llvm::DenseMap<const Decl*, AttrVec*> DeclAttrs;
 
   /// A mapping from non-redeclarable declarations in modules that were
   /// merged with other declarations to the canonical declaration that they were
   /// merged into.
   llvm::DenseMap<Decl*, Decl*> MergedDecls;
 
   /// A mapping from a defining declaration to a list of modules (other
   /// than the owning module of the declaration) that contain merged
   /// definitions of that entity.
   llvm::DenseMap<NamedDecl*, llvm::TinyPtrVector<Module*>> MergedDefModules;
 
   /// Initializers for a module, in order. Each Decl will be either
   /// something that has a semantic effect on startup (such as a variable with
   /// a non-constant initializer), or an ImportDecl (which recursively triggers
   /// initialization of another module).
   struct PerModuleInitializers {
     llvm::SmallVector<Decl*, 4> Initializers;
     llvm::SmallVector<GlobalDeclID, 4> LazyInitializers;
 
     void resolve(ASTContext &Ctx);
   };
   llvm::DenseMap<Module*, PerModuleInitializers*> ModuleInitializers;
 
   /// This is the top-level (C++20) Named module we are building.
   Module *CurrentCXXNamedModule = nullptr;
 
   /// Help structures to decide whether two `const Module *` belongs
   /// to the same conceptual module to avoid the expensive to string comparison
   /// if possible.
   ///
   /// Not serialized intentionally.
   llvm::StringMap<const Module *> PrimaryModuleNameMap;
   llvm::DenseMap<const Module *, const Module *> SameModuleLookupSet;
 
   static constexpr unsigned ConstantArrayTypesLog2InitSize = 8;
   static constexpr unsigned GeneralTypesLog2InitSize = 9;
   static constexpr unsigned FunctionProtoTypesLog2InitSize = 12;
 
   ASTContext &this_() { return *this; }
 
 public:
   /// A type synonym for the TemplateOrInstantiation mapping.
   using TemplateOrSpecializationInfo =
       llvm::PointerUnion<VarTemplateDecl *, MemberSpecializationInfo *>;
 
 private:
   friend class ASTDeclReader;
   friend class ASTReader;
   friend class ASTWriter;
   template <class> friend class serialization::AbstractTypeReader;
   friend class CXXRecordDecl;
   friend class IncrementalParser;
 
   /// A mapping to contain the template or declaration that
   /// a variable declaration describes or was instantiated from,
   /// respectively.
   ///
   /// For non-templates, this value will be NULL. For variable
   /// declarations that describe a variable template, this will be a
   /// pointer to a VarTemplateDecl. For static data members
   /// of class template specializations, this will be the
   /// MemberSpecializationInfo referring to the member variable that was
   /// instantiated or specialized. Thus, the mapping will keep track of
   /// the static data member templates from which static data members of
   /// class template specializations were instantiated.
   ///
   /// Given the following example:
   ///
   /// \code
   /// template<typename T>
   /// struct X {
   ///   static T value;
   /// };
   ///
   /// template<typename T>
   ///   T X<T>::value = T(17);
   ///
   /// int *x = &X<int>::value;
   /// \endcode
   ///
   /// This mapping will contain an entry that maps from the VarDecl for
   /// X<int>::value to the corresponding VarDecl for X<T>::value (within the
   /// class template X) and will be marked TSK_ImplicitInstantiation.
   llvm::DenseMap<const VarDecl *, TemplateOrSpecializationInfo>
   TemplateOrInstantiation;
 
   /// Keeps track of the declaration from which a using declaration was
   /// created during instantiation.
   ///
   /// The source and target declarations are always a UsingDecl, an
   /// UnresolvedUsingValueDecl, or an UnresolvedUsingTypenameDecl.
   ///
   /// For example:
   /// \code
   /// template<typename T>
   /// struct A {
   ///   void f();
   /// };
   ///
   /// template<typename T>
   /// struct B : A<T> {
   ///   using A<T>::f;
   /// };
   ///
   /// template struct B<int>;
   /// \endcode
   ///
   /// This mapping will contain an entry that maps from the UsingDecl in
   /// B<int> to the UnresolvedUsingDecl in B<T>.
   llvm::DenseMap<NamedDecl *, NamedDecl *> InstantiatedFromUsingDecl;
 
   /// Like InstantiatedFromUsingDecl, but for using-enum-declarations. Maps
   /// from the instantiated using-enum to the templated decl from whence it
   /// came.
   /// Note that using-enum-declarations cannot be dependent and
   /// thus will never be instantiated from an "unresolved"
   /// version thereof (as with using-declarations), so each mapping is from
   /// a (resolved) UsingEnumDecl to a (resolved) UsingEnumDecl.
   llvm::DenseMap<UsingEnumDecl *, UsingEnumDecl *>
       InstantiatedFromUsingEnumDecl;
 
   /// Simlarly maps instantiated UsingShadowDecls to their origin.
   llvm::DenseMap<UsingShadowDecl*, UsingShadowDecl*>
     InstantiatedFromUsingShadowDecl;
 
   llvm::DenseMap<FieldDecl *, FieldDecl *> InstantiatedFromUnnamedFieldDecl;
 
   /// Mapping that stores the methods overridden by a given C++
   /// member function.
   ///
   /// Since most C++ member functions aren't virtual and therefore
   /// don't override anything, we store the overridden functions in
   /// this map on the side rather than within the CXXMethodDecl structure.
   using CXXMethodVector = llvm::TinyPtrVector<const CXXMethodDecl *>;
   llvm::DenseMap<const CXXMethodDecl *, CXXMethodVector> OverriddenMethods;
 
   /// Mapping from each declaration context to its corresponding
   /// mangling numbering context (used for constructs like lambdas which
   /// need to be consistently numbered for the mangler).
   llvm::DenseMap<const DeclContext *, std::unique_ptr<MangleNumberingContext>>
       MangleNumberingContexts;
   llvm::DenseMap<const Decl *, std::unique_ptr<MangleNumberingContext>>
       ExtraMangleNumberingContexts;
 
   /// Side-table of mangling numbers for declarations which rarely
   /// need them (like static local vars).
   llvm::MapVector<const NamedDecl *, unsigned> MangleNumbers;
   llvm::MapVector<const VarDecl *, unsigned> StaticLocalNumbers;
   /// Mapping the associated device lambda mangling number if present.
   mutable llvm::DenseMap<const CXXRecordDecl *, unsigned>
       DeviceLambdaManglingNumbers;
 
   /// Mapping that stores parameterIndex values for ParmVarDecls when
   /// that value exceeds the bitfield size of ParmVarDeclBits.ParameterIndex.
   using ParameterIndexTable = llvm::DenseMap<const VarDecl *, unsigned>;
   ParameterIndexTable ParamIndices;
 
   ImportDecl *FirstLocalImport = nullptr;
   ImportDecl *LastLocalImport = nullptr;
 
   TranslationUnitDecl *TUDecl = nullptr;
   mutable ExternCContextDecl *ExternCContext = nullptr;
   mutable BuiltinTemplateDecl *MakeIntegerSeqDecl = nullptr;
   mutable BuiltinTemplateDecl *TypePackElementDecl = nullptr;
   mutable BuiltinTemplateDecl *BuiltinCommonTypeDecl = nullptr;
 
   /// The associated SourceManager object.
   SourceManager &SourceMgr;
 
   /// The language options used to create the AST associated with
   ///  this ASTContext object.
   LangOptions &LangOpts;
 
   /// NoSanitizeList object that is used by sanitizers to decide which
   /// entities should not be instrumented.
   std::unique_ptr<NoSanitizeList> NoSanitizeL;
 
   /// Function filtering mechanism to determine whether a given function
   /// should be imbued with the XRay "always" or "never" attributes.
   std::unique_ptr<XRayFunctionFilter> XRayFilter;
 
   /// ProfileList object that is used by the profile instrumentation
   /// to decide which entities should be instrumented.
   std::unique_ptr<ProfileList> ProfList;
 
   /// The allocator used to create AST objects.
   ///
   /// AST objects are never destructed; rather, all memory associated with the
   /// AST objects will be released when the ASTContext itself is destroyed.
   mutable llvm::BumpPtrAllocator BumpAlloc;
 
   /// Allocator for partial diagnostics.
   PartialDiagnostic::DiagStorageAllocator DiagAllocator;
 
   /// The current C++ ABI.
   std::unique_ptr<CXXABI> ABI;
   CXXABI *createCXXABI(const TargetInfo &T);
 
   /// Address space map mangling must be used with language specific
   /// address spaces (e.g. OpenCL/CUDA)
   bool AddrSpaceMapMangling;
 
   /// For performance, track whether any function effects are in use.
   mutable bool AnyFunctionEffects = false;
 
   const TargetInfo *Target = nullptr;
   const TargetInfo *AuxTarget = nullptr;
   clang::PrintingPolicy PrintingPolicy;
   std::unique_ptr<interp::Context> InterpContext;
   std::unique_ptr<ParentMapContext> ParentMapCtx;
 
   /// Keeps track of the deallocated DeclListNodes for future reuse.
   DeclListNode *ListNodeFreeList = nullptr;
 
 public:
   IdentifierTable &Idents;
   SelectorTable &Selectors;
   Builtin::Context &BuiltinInfo;
   const TranslationUnitKind TUKind;
   mutable DeclarationNameTable DeclarationNames;
   IntrusiveRefCntPtr<ExternalASTSource> ExternalSource;
   ASTMutationListener *Listener = nullptr;
 
   /// Returns the clang bytecode interpreter context.
   interp::Context &getInterpContext();
 
   struct CUDAConstantEvalContext {
     /// Do not allow wrong-sided variables in constant expressions.
     bool NoWrongSidedVars = false;
   } CUDAConstantEvalCtx;
   struct CUDAConstantEvalContextRAII {
     ASTContext &Ctx;
     CUDAConstantEvalContext SavedCtx;
     CUDAConstantEvalContextRAII(ASTContext &Ctx_, bool NoWrongSidedVars)
         : Ctx(Ctx_), SavedCtx(Ctx_.CUDAConstantEvalCtx) {
       Ctx_.CUDAConstantEvalCtx.NoWrongSidedVars = NoWrongSidedVars;
     }
     ~CUDAConstantEvalContextRAII() { Ctx.CUDAConstantEvalCtx = SavedCtx; }
   };
 
   /// Returns the dynamic AST node parent map context.
   ParentMapContext &getParentMapContext();
 
   // A traversal scope limits the parts of the AST visible to certain analyses.
   // RecursiveASTVisitor only visits specified children of TranslationUnitDecl.
   // getParents() will only observe reachable parent edges.
   //
   // The scope is defined by a set of "top-level" declarations which will be
   // visible under the TranslationUnitDecl.
   // Initially, it is the entire TU, represented by {getTranslationUnitDecl()}.
   //
   // After setTraversalScope({foo, bar}), the exposed AST looks like:
   // TranslationUnitDecl
   //  - foo
   //    - ...
   //  - bar
   //    - ...
   // All other siblings of foo and bar are pruned from the tree.
   // (However they are still accessible via TranslationUnitDecl->decls())
   //
   // Changing the scope clears the parent cache, which is expensive to rebuild.
   std::vector<Decl *> getTraversalScope() const { return TraversalScope; }
   void setTraversalScope(const std::vector<Decl *> &);
 
   /// Forwards to get node parents from the ParentMapContext. New callers should
   /// use ParentMapContext::getParents() directly.
   template <typename NodeT> DynTypedNodeList getParents(const NodeT &Node);
 
   const clang::PrintingPolicy &getPrintingPolicy() const {
     return PrintingPolicy;
   }
 
   void setPrintingPolicy(const clang::PrintingPolicy &Policy) {
     PrintingPolicy = Policy;
   }
 
   SourceManager& getSourceManager() { return SourceMgr; }
   const SourceManager& getSourceManager() const { return SourceMgr; }
 
   // Cleans up some of the data structures. This allows us to do cleanup
   // normally done in the destructor earlier. Renders much of the ASTContext
   // unusable, mostly the actual AST nodes, so should be called when we no
   // longer need access to the AST.
   void cleanup();
 
   llvm::BumpPtrAllocator &getAllocator() const {
     return BumpAlloc;
   }
 
   void *Allocate(size_t Size, unsigned Align = 8) const {
     return BumpAlloc.Allocate(Size, Align);
   }
   template <typename T> T *Allocate(size_t Num = 1) const {
     return static_cast<T *>(Allocate(Num * sizeof(T), alignof(T)));
   }
   void Deallocate(void *Ptr) const {}
 
   llvm::StringRef backupStr(llvm::StringRef S) const {
     char *Buf = new (*this) char[S.size()];
     std::copy(S.begin(), S.end(), Buf);
     return llvm::StringRef(Buf, S.size());
   }
 
   /// Allocates a \c DeclListNode or returns one from the \c ListNodeFreeList
   /// pool.
   DeclListNode *AllocateDeclListNode(clang::NamedDecl *ND) {
     if (DeclListNode *Alloc = ListNodeFreeList) {
       ListNodeFreeList = dyn_cast_if_present<DeclListNode *>(Alloc->Rest);
       Alloc->D = ND;
       Alloc->Rest = nullptr;
       return Alloc;
     }
     return new (*this) DeclListNode(ND);
   }
   /// Deallcates a \c DeclListNode by returning it to the \c ListNodeFreeList
   /// pool.
   void DeallocateDeclListNode(DeclListNode *N) {
     N->Rest = ListNodeFreeList;
     ListNodeFreeList = N;
   }
 
   /// Return the total amount of physical memory allocated for representing
   /// AST nodes and type information.
   size_t getASTAllocatedMemory() const {
     return BumpAlloc.getTotalMemory();
   }
 
   /// Return the total memory used for various side tables.
   size_t getSideTableAllocatedMemory() const;
 
   PartialDiagnostic::DiagStorageAllocator &getDiagAllocator() {
     return DiagAllocator;
   }
 
   const TargetInfo &getTargetInfo() const { return *Target; }
   const TargetInfo *getAuxTargetInfo() const { return AuxTarget; }
 
   const QualType GetHigherPrecisionFPType(QualType ElementType) const {
     const auto *CurrentBT = cast<BuiltinType>(ElementType);
     switch (CurrentBT->getKind()) {
     case BuiltinType::Kind::Half:
     case BuiltinType::Kind::Float16:
       return FloatTy;
     case BuiltinType::Kind::Float:
     case BuiltinType::Kind::BFloat16:
       return DoubleTy;
     case BuiltinType::Kind::Double:
       return LongDoubleTy;
     default:
       return ElementType;
     }
     return ElementType;
   }
 
   /// getIntTypeForBitwidth -
   /// sets integer QualTy according to specified details:
   /// bitwidth, signed/unsigned.
   /// Returns empty type if there is no appropriate target types.
   QualType getIntTypeForBitwidth(unsigned DestWidth,
                                  unsigned Signed) const;
 
   /// getRealTypeForBitwidth -
   /// sets floating point QualTy according to specified bitwidth.
   /// Returns empty type if there is no appropriate target types.
   QualType getRealTypeForBitwidth(unsigned DestWidth,
                                   FloatModeKind ExplicitType) const;
 
   bool AtomicUsesUnsupportedLibcall(const AtomicExpr *E) const;
 
   const LangOptions& getLangOpts() const { return LangOpts; }
 
   // If this condition is false, typo correction must be performed eagerly
   // rather than delayed in many places, as it makes use of dependent types.
   // the condition is false for clang's C-only codepath, as it doesn't support
   // dependent types yet.
   bool isDependenceAllowed() const {
     return LangOpts.CPlusPlus || LangOpts.RecoveryAST;
   }
 
   const NoSanitizeList &getNoSanitizeList() const { return *NoSanitizeL; }
 
   bool isTypeIgnoredBySanitizer(const SanitizerMask &Mask,
                                 const QualType &Ty) const;
 
   const XRayFunctionFilter &getXRayFilter() const {
     return *XRayFilter;
   }
 
   const ProfileList &getProfileList() const { return *ProfList; }
 
   DiagnosticsEngine &getDiagnostics() const;
 
   FullSourceLoc getFullLoc(SourceLocation Loc) const {
     return FullSourceLoc(Loc,SourceMgr);
   }
 
   /// Return the C++ ABI kind that should be used. The C++ ABI can be overriden
   /// at compile time with `-fc++-abi=`. If this is not provided, we instead use
   /// the default ABI set by the target.
   TargetCXXABI::Kind getCXXABIKind() const;
 
   /// All comments in this translation unit.
   RawCommentList Comments;
 
   /// True if comments are already loaded from ExternalASTSource.
   mutable bool CommentsLoaded = false;
 
   /// Mapping from declaration to directly attached comment.
   ///
   /// Raw comments are owned by Comments list.  This mapping is populated
   /// lazily.
   mutable llvm::DenseMap<const Decl *, const RawComment *> DeclRawComments;
 
   /// Mapping from canonical declaration to the first redeclaration in chain
   /// that has a comment attached.
   ///
   /// Raw comments are owned by Comments list.  This mapping is populated
   /// lazily.
   mutable llvm::DenseMap<const Decl *, const Decl *> RedeclChainComments;
 
   /// Keeps track of redeclaration chains that don't have any comment attached.
   /// Mapping from canonical declaration to redeclaration chain that has no
   /// comments attached to any redeclaration. Specifically it's mapping to
   /// the last redeclaration we've checked.
   ///
   /// Shall not contain declarations that have comments attached to any
   /// redeclaration in their chain.
   mutable llvm::DenseMap<const Decl *, const Decl *> CommentlessRedeclChains;
 
   /// Mapping from declarations to parsed comments attached to any
   /// redeclaration.
   mutable llvm::DenseMap<const Decl *, comments::FullComment *> ParsedComments;
 
   /// Attaches \p Comment to \p OriginalD and to its redeclaration chain
   /// and removes the redeclaration chain from the set of commentless chains.
   ///
   /// Don't do anything if a comment has already been attached to \p OriginalD
   /// or its redeclaration chain.
   void cacheRawCommentForDecl(const Decl &OriginalD,
                               const RawComment &Comment) const;
 
   /// \returns searches \p CommentsInFile for doc comment for \p D.
   ///
   /// \p RepresentativeLocForDecl is used as a location for searching doc
   /// comments. \p CommentsInFile is a mapping offset -> comment of files in the
   /// same file where \p RepresentativeLocForDecl is.
   RawComment *getRawCommentForDeclNoCacheImpl(
       const Decl *D, const SourceLocation RepresentativeLocForDecl,
       const std::map<unsigned, RawComment *> &CommentsInFile) const;
 
   /// Return the documentation comment attached to a given declaration,
   /// without looking into cache.
   RawComment *getRawCommentForDeclNoCache(const Decl *D) const;
 
 public:
   void addComment(const RawComment &RC);
 
   /// Return the documentation comment attached to a given declaration.
   /// Returns nullptr if no comment is attached.
   ///
   /// \param OriginalDecl if not nullptr, is set to declaration AST node that
   /// had the comment, if the comment we found comes from a redeclaration.
   const RawComment *
   getRawCommentForAnyRedecl(const Decl *D,
                             const Decl **OriginalDecl = nullptr) const;
 
   /// Searches existing comments for doc comments that should be attached to \p
   /// Decls. If any doc comment is found, it is parsed.
   ///
   /// Requirement: All \p Decls are in the same file.
   ///
   /// If the last comment in the file is already attached we assume
   /// there are not comments left to be attached to \p Decls.
   void attachCommentsToJustParsedDecls(ArrayRef<Decl *> Decls,
                                        const Preprocessor *PP);
 
   /// Return parsed documentation comment attached to a given declaration.
   /// Returns nullptr if no comment is attached.
   ///
   /// \param PP the Preprocessor used with this TU.  Could be nullptr if
   /// preprocessor is not available.
   comments::FullComment *getCommentForDecl(const Decl *D,
                                            const Preprocessor *PP) const;
 
   /// Return parsed documentation comment attached to a given declaration.
   /// Returns nullptr if no comment is attached. Does not look at any
   /// redeclarations of the declaration.
   comments::FullComment *getLocalCommentForDeclUncached(const Decl *D) const;
 
   comments::FullComment *cloneFullComment(comments::FullComment *FC,
                                          const Decl *D) const;
 
 private:
   mutable comments::CommandTraits CommentCommandTraits;
 
   /// Iterator that visits import declarations.
   class import_iterator {
     ImportDecl *Import = nullptr;
 
   public:
     using value_type = ImportDecl *;
     using reference = ImportDecl *;
     using pointer = ImportDecl *;
     using difference_type = int;
     using iterator_category = std::forward_iterator_tag;
 
     import_iterator() = default;
     explicit import_iterator(ImportDecl *Import) : Import(Import) {}
 
     reference operator*() const { return Import; }
     pointer operator->() const { return Import; }
 
     import_iterator &operator++() {
       Import = ASTContext::getNextLocalImport(Import);
       return *this;
     }
 
     import_iterator operator++(int) {
       import_iterator Other(*this);
       ++(*this);
       return Other;
     }
 
     friend bool operator==(import_iterator X, import_iterator Y) {
       return X.Import == Y.Import;
     }
 
     friend bool operator!=(import_iterator X, import_iterator Y) {
       return X.Import != Y.Import;
     }
   };
 
 public:
   comments::CommandTraits &getCommentCommandTraits() const {
     return CommentCommandTraits;
   }
 
   /// Retrieve the attributes for the given declaration.
   AttrVec& getDeclAttrs(const Decl *D);
 
   /// Erase the attributes corresponding to the given declaration.
   void eraseDeclAttrs(const Decl *D);
 
   /// If this variable is an instantiated static data member of a
   /// class template specialization, returns the templated static data member
   /// from which it was instantiated.
   // FIXME: Remove ?
   MemberSpecializationInfo *getInstantiatedFromStaticDataMember(
                                                            const VarDecl *Var);
 
   /// Note that the static data member \p Inst is an instantiation of
   /// the static data member template \p Tmpl of a class template.
   void setInstantiatedFromStaticDataMember(VarDecl *Inst, VarDecl *Tmpl,
                                            TemplateSpecializationKind TSK,
                         SourceLocation PointOfInstantiation = SourceLocation());
 
   TemplateOrSpecializationInfo
   getTemplateOrSpecializationInfo(const VarDecl *Var);
 
   void setTemplateOrSpecializationInfo(VarDecl *Inst,
                                        TemplateOrSpecializationInfo TSI);
 
   /// If the given using decl \p Inst is an instantiation of
   /// another (possibly unresolved) using decl, return it.
   NamedDecl *getInstantiatedFromUsingDecl(NamedDecl *Inst);
 
   /// Remember that the using decl \p Inst is an instantiation
   /// of the using decl \p Pattern of a class template.
   void setInstantiatedFromUsingDecl(NamedDecl *Inst, NamedDecl *Pattern);
 
   /// If the given using-enum decl \p Inst is an instantiation of
   /// another using-enum decl, return it.
   UsingEnumDecl *getInstantiatedFromUsingEnumDecl(UsingEnumDecl *Inst);
 
   /// Remember that the using enum decl \p Inst is an instantiation
   /// of the using enum decl \p Pattern of a class template.
   void setInstantiatedFromUsingEnumDecl(UsingEnumDecl *Inst,
                                         UsingEnumDecl *Pattern);
 
   UsingShadowDecl *getInstantiatedFromUsingShadowDecl(UsingShadowDecl *Inst);
   void setInstantiatedFromUsingShadowDecl(UsingShadowDecl *Inst,
                                           UsingShadowDecl *Pattern);
 
   FieldDecl *getInstantiatedFromUnnamedFieldDecl(FieldDecl *Field) const;
 
   void setInstantiatedFromUnnamedFieldDecl(FieldDecl *Inst, FieldDecl *Tmpl);
 
   // Access to the set of methods overridden by the given C++ method.
   using overridden_cxx_method_iterator = CXXMethodVector::const_iterator;
   overridden_cxx_method_iterator
   overridden_methods_begin(const CXXMethodDecl *Method) const;
 
   overridden_cxx_method_iterator
   overridden_methods_end(const CXXMethodDecl *Method) const;
 
   unsigned overridden_methods_size(const CXXMethodDecl *Method) const;
 
   using overridden_method_range =
       llvm::iterator_range<overridden_cxx_method_iterator>;
 
   overridden_method_range overridden_methods(const CXXMethodDecl *Method) const;
 
   /// Note that the given C++ \p Method overrides the given \p
   /// Overridden method.
   void addOverriddenMethod(const CXXMethodDecl *Method,
                            const CXXMethodDecl *Overridden);
 
   /// Return C++ or ObjC overridden methods for the given \p Method.
   ///
   /// An ObjC method is considered to override any method in the class's
   /// base classes, its protocols, or its categories' protocols, that has
   /// the same selector and is of the same kind (class or instance).
   /// A method in an implementation is not considered as overriding the same
   /// method in the interface or its categories.
   void getOverriddenMethods(
                         const NamedDecl *Method,
                         SmallVectorImpl<const NamedDecl *> &Overridden) const;
 
   /// Notify the AST context that a new import declaration has been
   /// parsed or implicitly created within this translation unit.
   void addedLocalImportDecl(ImportDecl *Import);
 
   static ImportDecl *getNextLocalImport(ImportDecl *Import) {
     return Import->getNextLocalImport();
   }
 
   using import_range = llvm::iterator_range<import_iterator>;
 
   import_range local_imports() const {
     return import_range(import_iterator(FirstLocalImport), import_iterator());
   }
 
   Decl *getPrimaryMergedDecl(Decl *D) {
     Decl *Result = MergedDecls.lookup(D);
     return Result ? Result : D;
   }
   void setPrimaryMergedDecl(Decl *D, Decl *Primary) {
     MergedDecls[D] = Primary;
   }
 
   /// Note that the definition \p ND has been merged into module \p M,
   /// and should be visible whenever \p M is visible.
   void mergeDefinitionIntoModule(NamedDecl *ND, Module *M,
                                  bool NotifyListeners = true);
 
   /// Clean up the merged definition list. Call this if you might have
   /// added duplicates into the list.
   void deduplicateMergedDefinitonsFor(NamedDecl *ND);
 
   /// Get the additional modules in which the definition \p Def has
   /// been merged.
   ArrayRef<Module*> getModulesWithMergedDefinition(const NamedDecl *Def);
 
   /// Add a declaration to the list of declarations that are initialized
   /// for a module. This will typically be a global variable (with internal
   /// linkage) that runs module initializers, such as the iostream initializer,
   /// or an ImportDecl nominating another module that has initializers.
   void addModuleInitializer(Module *M, Decl *Init);
 
   void addLazyModuleInitializers(Module *M, ArrayRef<GlobalDeclID> IDs);
 
   /// Get the initializations to perform when importing a module, if any.
   ArrayRef<Decl*> getModuleInitializers(Module *M);
 
   /// Set the (C++20) module we are building.
   void setCurrentNamedModule(Module *M);
 
   /// Get module under construction, nullptr if this is not a C++20 module.
   Module *getCurrentNamedModule() const { return CurrentCXXNamedModule; }
 
   /// If the two module \p M1 and \p M2 are in the same module.
   ///
   /// FIXME: The signature may be confusing since `clang::Module` means to
   /// a module fragment or a module unit but not a C++20 module.
   bool isInSameModule(const Module *M1, const Module *M2);
 
   TranslationUnitDecl *getTranslationUnitDecl() const {
     return TUDecl->getMostRecentDecl();
   }
   void addTranslationUnitDecl() {
     assert(!TUDecl || TUKind == TU_Incremental);
     TranslationUnitDecl *NewTUDecl = TranslationUnitDecl::Create(*this);
     if (TraversalScope.empty() || TraversalScope.back() == TUDecl)
       TraversalScope = {NewTUDecl};
     if (TUDecl)
       NewTUDecl->setPreviousDecl(TUDecl);
     TUDecl = NewTUDecl;
   }
 
   ExternCContextDecl *getExternCContextDecl() const;
   BuiltinTemplateDecl *getMakeIntegerSeqDecl() const;
   BuiltinTemplateDecl *getTypePackElementDecl() const;
   BuiltinTemplateDecl *getBuiltinCommonTypeDecl() const;
 
   // Builtin Types.
   CanQualType VoidTy;
   CanQualType BoolTy;
   CanQualType CharTy;
   CanQualType WCharTy;  // [C++ 3.9.1p5].
   CanQualType WideCharTy; // Same as WCharTy in C++, integer type in C99.
   CanQualType WIntTy;   // [C99 7.24.1], integer type unchanged by default promotions.
   CanQualType Char8Ty;  // [C++20 proposal]
   CanQualType Char16Ty; // [C++0x 3.9.1p5], integer type in C99.
   CanQualType Char32Ty; // [C++0x 3.9.1p5], integer type in C99.
   CanQualType SignedCharTy, ShortTy, IntTy, LongTy, LongLongTy, Int128Ty;
   CanQualType UnsignedCharTy, UnsignedShortTy, UnsignedIntTy, UnsignedLongTy;
   CanQualType UnsignedLongLongTy, UnsignedInt128Ty;
   CanQualType FloatTy, DoubleTy, LongDoubleTy, Float128Ty, Ibm128Ty;
   CanQualType ShortAccumTy, AccumTy,
       LongAccumTy;  // ISO/IEC JTC1 SC22 WG14 N1169 Extension
   CanQualType UnsignedShortAccumTy, UnsignedAccumTy, UnsignedLongAccumTy;
   CanQualType ShortFractTy, FractTy, LongFractTy;
   CanQualType UnsignedShortFractTy, UnsignedFractTy, UnsignedLongFractTy;
   CanQualType SatShortAccumTy, SatAccumTy, SatLongAccumTy;
   CanQualType SatUnsignedShortAccumTy, SatUnsignedAccumTy,
       SatUnsignedLongAccumTy;
   CanQualType SatShortFractTy, SatFractTy, SatLongFractTy;
   CanQualType SatUnsignedShortFractTy, SatUnsignedFractTy,
       SatUnsignedLongFractTy;
   CanQualType HalfTy; // [OpenCL 6.1.1.1], ARM NEON
   CanQualType BFloat16Ty;
   CanQualType Float16Ty; // C11 extension ISO/IEC TS 18661-3
   CanQualType VoidPtrTy, NullPtrTy;
   CanQualType DependentTy, OverloadTy, BoundMemberTy, UnresolvedTemplateTy,
       UnknownAnyTy;
   CanQualType BuiltinFnTy;
   CanQualType PseudoObjectTy, ARCUnbridgedCastTy;
   CanQualType ObjCBuiltinIdTy, ObjCBuiltinClassTy, ObjCBuiltinSelTy;
   CanQualType ObjCBuiltinBoolTy;
 #define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix) \
   CanQualType SingletonId;
 #include "clang/Basic/OpenCLImageTypes.def"
   CanQualType OCLSamplerTy, OCLEventTy, OCLClkEventTy;
   CanQualType OCLQueueTy, OCLReserveIDTy;
   CanQualType IncompleteMatrixIdxTy;
   CanQualType ArraySectionTy;
   CanQualType OMPArrayShapingTy, OMPIteratorTy;
 #define EXT_OPAQUE_TYPE(ExtType, Id, Ext) \
   CanQualType Id##Ty;
 #include "clang/Basic/OpenCLExtensionTypes.def"
 #define SVE_TYPE(Name, Id, SingletonId) \
   CanQualType SingletonId;
 #include "clang/Basic/AArch64SVEACLETypes.def"
 #define PPC_VECTOR_TYPE(Name, Id, Size) \
   CanQualType Id##Ty;
 #include "clang/Basic/PPCTypes.def"
 #define RVV_TYPE(Name, Id, SingletonId) \
   CanQualType SingletonId;
 #include "clang/Basic/RISCVVTypes.def"
 #define WASM_TYPE(Name, Id, SingletonId) CanQualType SingletonId;
 #include "clang/Basic/WebAssemblyReferenceTypes.def"
 #define AMDGPU_TYPE(Name, Id, SingletonId, Width, Align)                       \
   CanQualType SingletonId;
 #include "clang/Basic/AMDGPUTypes.def"
 #define HLSL_INTANGIBLE_TYPE(Name, Id, SingletonId) CanQualType SingletonId;
 #include "clang/Basic/HLSLIntangibleTypes.def"
 
   // Types for deductions in C++0x [stmt.ranged]'s desugaring. Built on demand.
   mutable QualType AutoDeductTy;     // Deduction against 'auto'.
   mutable QualType AutoRRefDeductTy; // Deduction against 'auto &&'.
 
   // Decl used to help define __builtin_va_list for some targets.
   // The decl is built when constructing 'BuiltinVaListDecl'.
   mutable Decl *VaListTagDecl = nullptr;
 
   // Implicitly-declared type 'struct _GUID'.
   mutable TagDecl *MSGuidTagDecl = nullptr;
 
   /// Keep track of CUDA/HIP device-side variables ODR-used by host code.
   /// This does not include extern shared variables used by device host
   /// functions as addresses of shared variables are per warp, therefore
   /// cannot be accessed by host code.
   llvm::DenseSet<const VarDecl *> CUDADeviceVarODRUsedByHost;
 
   /// Keep track of CUDA/HIP external kernels or device variables ODR-used by
   /// host code. SetVector is used to maintain the order.
   llvm::SetVector<const ValueDecl *> CUDAExternalDeviceDeclODRUsedByHost;
 
   /// Keep track of CUDA/HIP implicit host device functions used on device side
   /// in device compilation.
   llvm::DenseSet<const FunctionDecl *> CUDAImplicitHostDeviceFunUsedByDevice;
 
   /// Map of SYCL kernels indexed by the unique type used to name the kernel.
   /// Entries are not serialized but are recreated on deserialization of a
   /// sycl_kernel_entry_point attributed function declaration.
   llvm::DenseMap<CanQualType, SYCLKernelInfo> SYCLKernels;
 
   /// For capturing lambdas with an explicit object parameter whose type is
   /// derived from the lambda type, we need to perform derived-to-base
   /// conversion so we can access the captures; the cast paths for that
   /// are stored here.
   llvm::DenseMap<const CXXMethodDecl *, CXXCastPath> LambdaCastPaths;
 
   ASTContext(LangOptions &LOpts, SourceManager &SM, IdentifierTable &idents,
              SelectorTable &sels, Builtin::Context &builtins,
              TranslationUnitKind TUKind);
   ASTContext(const ASTContext &) = delete;
   ASTContext &operator=(const ASTContext &) = delete;
   ~ASTContext();
 
   /// Attach an external AST source to the AST context.
   ///
   /// The external AST source provides the ability to load parts of
   /// the abstract syntax tree as needed from some external storage,
   /// e.g., a precompiled header.
   void setExternalSource(IntrusiveRefCntPtr<ExternalASTSource> Source);
 
   /// Retrieve a pointer to the external AST source associated
   /// with this AST context, if any.
   ExternalASTSource *getExternalSource() const {
     return ExternalSource.get();
   }
 
   /// Attach an AST mutation listener to the AST context.
   ///
   /// The AST mutation listener provides the ability to track modifications to
   /// the abstract syntax tree entities committed after they were initially
   /// created.
   void setASTMutationListener(ASTMutationListener *Listener) {
     this->Listener = Listener;
   }
 
   /// Retrieve a pointer to the AST mutation listener associated
   /// with this AST context, if any.
   ASTMutationListener *getASTMutationListener() const { return Listener; }
 
   void PrintStats() const;
   const SmallVectorImpl<Type *>& getTypes() const { return Types; }
 
   BuiltinTemplateDecl *buildBuiltinTemplateDecl(BuiltinTemplateKind BTK,
                                                 const IdentifierInfo *II) const;
 
   /// Create a new implicit TU-level CXXRecordDecl or RecordDecl
   /// declaration.
   RecordDecl *buildImplicitRecord(
       StringRef Name,
       RecordDecl::TagKind TK = RecordDecl::TagKind::Struct) const;
 
   /// Create a new implicit TU-level typedef declaration.
   TypedefDecl *buildImplicitTypedef(QualType T, StringRef Name) const;
 
   /// Retrieve the declaration for the 128-bit signed integer type.
   TypedefDecl *getInt128Decl() const;
 
   /// Retrieve the declaration for the 128-bit unsigned integer type.
   TypedefDecl *getUInt128Decl() const;
 
   //===--------------------------------------------------------------------===//
   //                           Type Constructors
   //===--------------------------------------------------------------------===//
 
 private:
   /// Return a type with extended qualifiers.
   QualType getExtQualType(const Type *Base, Qualifiers Quals) const;
 
   QualType getTypeDeclTypeSlow(const TypeDecl *Decl) const;
 
   QualType getPipeType(QualType T, bool ReadOnly) const;
 
 public:
   /// Return the uniqued reference to the type for an address space
   /// qualified type with the specified type and address space.
   ///
   /// The resulting type has a union of the qualifiers from T and the address
   /// space. If T already has an address space specifier, it is silently
   /// replaced.
   QualType getAddrSpaceQualType(QualType T, LangAS AddressSpace) const;
 
   /// Remove any existing address space on the type and returns the type
   /// with qualifiers intact (or that's the idea anyway)
   ///
   /// The return type should be T with all prior qualifiers minus the address
   /// space.
   QualType removeAddrSpaceQualType(QualType T) const;
 
   /// Return the "other" discriminator used for the pointer auth schema used for
   /// vtable pointers in instances of the requested type.
   uint16_t
   getPointerAuthVTablePointerDiscriminator(const CXXRecordDecl *RD);
 
   /// Return the "other" type-specific discriminator for the given type.
   uint16_t getPointerAuthTypeDiscriminator(QualType T);
 
   /// Apply Objective-C protocol qualifiers to the given type.
   /// \param allowOnPointerType specifies if we can apply protocol
   /// qualifiers on ObjCObjectPointerType. It can be set to true when
   /// constructing the canonical type of a Objective-C type parameter.
   QualType applyObjCProtocolQualifiers(QualType type,
       ArrayRef<ObjCProtocolDecl *> protocols, bool &hasError,
       bool allowOnPointerType = false) const;
 
   /// Return the uniqued reference to the type for an Objective-C
   /// gc-qualified type.
   ///
   /// The resulting type has a union of the qualifiers from T and the gc
   /// attribute.
   QualType getObjCGCQualType(QualType T, Qualifiers::GC gcAttr) const;
 
   /// Remove the existing address space on the type if it is a pointer size
   /// address space and return the type with qualifiers intact.
   QualType removePtrSizeAddrSpace(QualType T) const;
 
   /// Return the uniqued reference to the type for a \c restrict
   /// qualified type.
   ///
   /// The resulting type has a union of the qualifiers from \p T and
   /// \c restrict.
   QualType getRestrictType(QualType T) const {
     return T.withFastQualifiers(Qualifiers::Restrict);
   }
 
   /// Return the uniqued reference to the type for a \c volatile
   /// qualified type.
   ///
   /// The resulting type has a union of the qualifiers from \p T and
   /// \c volatile.
   QualType getVolatileType(QualType T) const {
     return T.withFastQualifiers(Qualifiers::Volatile);
   }
 
   /// Return the uniqued reference to the type for a \c const
   /// qualified type.
   ///
   /// The resulting type has a union of the qualifiers from \p T and \c const.
   ///
   /// It can be reasonably expected that this will always be equivalent to
   /// calling T.withConst().
   QualType getConstType(QualType T) const { return T.withConst(); }
 
   /// Rebuild a type, preserving any existing type sugar. For function types,
   /// you probably want to just use \c adjustFunctionResultType and friends
   /// instead.
   QualType adjustType(QualType OldType,
                       llvm::function_ref<QualType(QualType)> Adjust) const;
 
   /// Change the ExtInfo on a function type.
   const FunctionType *adjustFunctionType(const FunctionType *Fn,
                                          FunctionType::ExtInfo EInfo);
 
   /// Change the result type of a function type, preserving sugar such as
   /// attributed types.
   QualType adjustFunctionResultType(QualType FunctionType,
                                     QualType NewResultType);
 
   /// Adjust the given function result type.
   CanQualType getCanonicalFunctionResultType(QualType ResultType) const;
 
   /// Change the result type of a function type once it is deduced.
   void adjustDeducedFunctionResultType(FunctionDecl *FD, QualType ResultType);
 
   /// Get a function type and produce the equivalent function type with the
   /// specified exception specification. Type sugar that can be present on a
   /// declaration of a function with an exception specification is permitted
   /// and preserved. Other type sugar (for instance, typedefs) is not.
   QualType getFunctionTypeWithExceptionSpec(
       QualType Orig, const FunctionProtoType::ExceptionSpecInfo &ESI) const;
 
   /// Determine whether two function types are the same, ignoring
   /// exception specifications in cases where they're part of the type.
   bool hasSameFunctionTypeIgnoringExceptionSpec(QualType T, QualType U) const;
 
   /// Change the exception specification on a function once it is
   /// delay-parsed, instantiated, or computed.
   void adjustExceptionSpec(FunctionDecl *FD,
                            const FunctionProtoType::ExceptionSpecInfo &ESI,
                            bool AsWritten = false);
 
   /// Get a function type and produce the equivalent function type where
   /// pointer size address spaces in the return type and parameter types are
   /// replaced with the default address space.
   QualType getFunctionTypeWithoutPtrSizes(QualType T);
 
   /// Determine whether two function types are the same, ignoring pointer sizes
   /// in the return type and parameter types.
   bool hasSameFunctionTypeIgnoringPtrSizes(QualType T, QualType U);
 
   /// Get or construct a function type that is equivalent to the input type
   /// except that the parameter ABI annotations are stripped.
   QualType getFunctionTypeWithoutParamABIs(QualType T) const;
 
   /// Determine if two function types are the same, ignoring parameter ABI
   /// annotations.
   bool hasSameFunctionTypeIgnoringParamABI(QualType T, QualType U) const;
 
   /// Return the uniqued reference to the type for a complex
   /// number with the specified element type.
   QualType getComplexType(QualType T) const;
   CanQualType getComplexType(CanQualType T) const {
     return CanQualType::CreateUnsafe(getComplexType((QualType) T));
   }
 
   /// Return the uniqued reference to the type for a pointer to
   /// the specified type.
   QualType getPointerType(QualType T) const;
   CanQualType getPointerType(CanQualType T) const {
     return CanQualType::CreateUnsafe(getPointerType((QualType) T));
   }
 
   QualType
   getCountAttributedType(QualType T, Expr *CountExpr, bool CountInBytes,
                          bool OrNull,
                          ArrayRef<TypeCoupledDeclRefInfo> DependentDecls) const;
 
   /// Return the uniqued reference to a type adjusted from the original
   /// type to a new type.
   QualType getAdjustedType(QualType Orig, QualType New) const;
   CanQualType getAdjustedType(CanQualType Orig, CanQualType New) const {
     return CanQualType::CreateUnsafe(
         getAdjustedType((QualType)Orig, (QualType)New));
   }
 
   /// Return the uniqued reference to the decayed version of the given
   /// type.  Can only be called on array and function types which decay to
   /// pointer types.
   QualType getDecayedType(QualType T) const;
   CanQualType getDecayedType(CanQualType T) const {
     return CanQualType::CreateUnsafe(getDecayedType((QualType) T));
   }
   /// Return the uniqued reference to a specified decay from the original
   /// type to the decayed type.
   QualType getDecayedType(QualType Orig, QualType Decayed) const;
 
   /// Return the uniqued reference to a specified array parameter type from the
   /// original array type.
   QualType getArrayParameterType(QualType Ty) const;
 
   /// Return the uniqued reference to the atomic type for the specified
   /// type.
   QualType getAtomicType(QualType T) const;
 
   /// Return the uniqued reference to the type for a block of the
   /// specified type.
   QualType getBlockPointerType(QualType T) const;
 
   /// Gets the struct used to keep track of the descriptor for pointer to
   /// blocks.
   QualType getBlockDescriptorType() const;
 
   /// Return a read_only pipe type for the specified type.
   QualType getReadPipeType(QualType T) const;
 
   /// Return a write_only pipe type for the specified type.
   QualType getWritePipeType(QualType T) const;
 
   /// Return a bit-precise integer type with the specified signedness and bit
   /// count.
   QualType getBitIntType(bool Unsigned, unsigned NumBits) const;
 
   /// Return a dependent bit-precise integer type with the specified signedness
   /// and bit count.
   QualType getDependentBitIntType(bool Unsigned, Expr *BitsExpr) const;
 
   /// Gets the struct used to keep track of the extended descriptor for
   /// pointer to blocks.
   QualType getBlockDescriptorExtendedType() const;
 
   /// Map an AST Type to an OpenCLTypeKind enum value.
   OpenCLTypeKind getOpenCLTypeKind(const Type *T) const;
 
   /// Get address space for OpenCL type.
   LangAS getOpenCLTypeAddrSpace(const Type *T) const;
 
   /// Returns default address space based on OpenCL version and enabled features
   inline LangAS getDefaultOpenCLPointeeAddrSpace() {
     return LangOpts.OpenCLGenericAddressSpace ? LangAS::opencl_generic
                                               : LangAS::opencl_private;
   }
 
   void setcudaConfigureCallDecl(FunctionDecl *FD) {
     cudaConfigureCallDecl = FD;
   }
 
   FunctionDecl *getcudaConfigureCallDecl() {
     return cudaConfigureCallDecl;
   }
 
   /// Returns true iff we need copy/dispose helpers for the given type.
   bool BlockRequiresCopying(QualType Ty, const VarDecl *D);
 
   /// Returns true, if given type has a known lifetime. HasByrefExtendedLayout
   /// is set to false in this case. If HasByrefExtendedLayout returns true,
   /// byref variable has extended lifetime.
   bool getByrefLifetime(QualType Ty,
                         Qualifiers::ObjCLifetime &Lifetime,
                         bool &HasByrefExtendedLayout) const;
 
   /// Return the uniqued reference to the type for an lvalue reference
   /// to the specified type.
   QualType getLValueReferenceType(QualType T, bool SpelledAsLValue = true)
     const;
 
   /// Return the uniqued reference to the type for an rvalue reference
   /// to the specified type.
   QualType getRValueReferenceType(QualType T) const;
 
   /// Return the uniqued reference to the type for a member pointer to
   /// the specified type in the specified class.
   ///
   /// The class \p Cls is a \c Type because it could be a dependent name.
   QualType getMemberPointerType(QualType T, const Type *Cls) const;
 
   /// Return a non-unique reference to the type for a variable array of
   /// the specified element type.
   QualType getVariableArrayType(QualType EltTy, Expr *NumElts,
                                 ArraySizeModifier ASM, unsigned IndexTypeQuals,
                                 SourceRange Brackets) const;
 
   /// Return a non-unique reference to the type for a dependently-sized
   /// array of the specified element type.
   ///
   /// FIXME: We will need these to be uniqued, or at least comparable, at some
   /// point.
   QualType getDependentSizedArrayType(QualType EltTy, Expr *NumElts,
                                       ArraySizeModifier ASM,
                                       unsigned IndexTypeQuals,
                                       SourceRange Brackets) const;
 
   /// Return a unique reference to the type for an incomplete array of
   /// the specified element type.
   QualType getIncompleteArrayType(QualType EltTy, ArraySizeModifier ASM,
                                   unsigned IndexTypeQuals) const;
 
   /// Return the unique reference to the type for a constant array of
   /// the specified element type.
   QualType getConstantArrayType(QualType EltTy, const llvm::APInt &ArySize,
                                 const Expr *SizeExpr, ArraySizeModifier ASM,
                                 unsigned IndexTypeQuals) const;
 
   /// Return a type for a constant array for a string literal of the
   /// specified element type and length.
   QualType getStringLiteralArrayType(QualType EltTy, unsigned Length) const;
 
   /// Returns a vla type where known sizes are replaced with [*].
   QualType getVariableArrayDecayedType(QualType Ty) const;
 
   // Convenience struct to return information about a builtin vector type.
   struct BuiltinVectorTypeInfo {
     QualType ElementType;
     llvm::ElementCount EC;
     unsigned NumVectors;
     BuiltinVectorTypeInfo(QualType ElementType, llvm::ElementCount EC,
                           unsigned NumVectors)
         : ElementType(ElementType), EC(EC), NumVectors(NumVectors) {}
   };
 
   /// Returns the element type, element count and number of vectors
   /// (in case of tuple) for a builtin vector type.
   BuiltinVectorTypeInfo
   getBuiltinVectorTypeInfo(const BuiltinType *VecTy) const;
 
   /// Return the unique reference to a scalable vector type of the specified
   /// element type and scalable number of elements.
   /// For RISC-V, number of fields is also provided when it fetching for
   /// tuple type.
   ///
   /// \pre \p EltTy must be a built-in type.
   QualType getScalableVectorType(QualType EltTy, unsigned NumElts,
                                  unsigned NumFields = 1) const;
 
   /// Return a WebAssembly externref type.
   QualType getWebAssemblyExternrefType() const;
 
   /// Return the unique reference to a vector type of the specified
   /// element type and size.
   ///
   /// \pre \p VectorType must be a built-in type.
   QualType getVectorType(QualType VectorType, unsigned NumElts,
                          VectorKind VecKind) const;
   /// Return the unique reference to the type for a dependently sized vector of
   /// the specified element type.
   QualType getDependentVectorType(QualType VectorType, Expr *SizeExpr,
                                   SourceLocation AttrLoc,
                                   VectorKind VecKind) const;
 
   /// Return the unique reference to an extended vector type
   /// of the specified element type and size.
   ///
   /// \pre \p VectorType must be a built-in type.
   QualType getExtVectorType(QualType VectorType, unsigned NumElts) const;
 
   /// \pre Return a non-unique reference to the type for a dependently-sized
   /// vector of the specified element type.
   ///
   /// FIXME: We will need these to be uniqued, or at least comparable, at some
   /// point.
   QualType getDependentSizedExtVectorType(QualType VectorType,
                                           Expr *SizeExpr,
                                           SourceLocation AttrLoc) const;
 
   /// Return the unique reference to the matrix type of the specified element
   /// type and size
   ///
   /// \pre \p ElementType must be a valid matrix element type (see
   /// MatrixType::isValidElementType).
   QualType getConstantMatrixType(QualType ElementType, unsigned NumRows,
                                  unsigned NumColumns) const;
 
   /// Return the unique reference to the matrix type of the specified element
   /// type and size
   QualType getDependentSizedMatrixType(QualType ElementType, Expr *RowExpr,
                                        Expr *ColumnExpr,
                                        SourceLocation AttrLoc) const;
 
   QualType getDependentAddressSpaceType(QualType PointeeType,
                                         Expr *AddrSpaceExpr,
                                         SourceLocation AttrLoc) const;
 
   /// Return a K&R style C function type like 'int()'.
   QualType getFunctionNoProtoType(QualType ResultTy,
                                   const FunctionType::ExtInfo &Info) const;
 
   QualType getFunctionNoProtoType(QualType ResultTy) const {
     return getFunctionNoProtoType(ResultTy, FunctionType::ExtInfo());
   }
 
   /// Return a normal function type with a typed argument list.
   QualType getFunctionType(QualType ResultTy, ArrayRef<QualType> Args,
                            const FunctionProtoType::ExtProtoInfo &EPI) const {
     return getFunctionTypeInternal(ResultTy, Args, EPI, false);
   }
 
   QualType adjustStringLiteralBaseType(QualType StrLTy) const;
 
 private:
   /// Return a normal function type with a typed argument list.
   QualType getFunctionTypeInternal(QualType ResultTy, ArrayRef<QualType> Args,
                                    const FunctionProtoType::ExtProtoInfo &EPI,
                                    bool OnlyWantCanonical) const;
   QualType
   getAutoTypeInternal(QualType DeducedType, AutoTypeKeyword Keyword,
                       bool IsDependent, bool IsPack = false,
                       ConceptDecl *TypeConstraintConcept = nullptr,
                       ArrayRef<TemplateArgument> TypeConstraintArgs = {},
                       bool IsCanon = false) const;
 
 public:
   /// Return the unique reference to the type for the specified type
   /// declaration.
   QualType getTypeDeclType(const TypeDecl *Decl,
                            const TypeDecl *PrevDecl = nullptr) const {
     assert(Decl && "Passed null for Decl param");
     if (Decl->TypeForDecl) return QualType(Decl->TypeForDecl, 0);
 
     if (PrevDecl) {
       assert(PrevDecl->TypeForDecl && "previous decl has no TypeForDecl");
       Decl->TypeForDecl = PrevDecl->TypeForDecl;
       return QualType(PrevDecl->TypeForDecl, 0);
     }
 
     return getTypeDeclTypeSlow(Decl);
   }
 
   QualType getUsingType(const UsingShadowDecl *Found,
                         QualType Underlying) const;
 
   /// Return the unique reference to the type for the specified
   /// typedef-name decl.
   QualType getTypedefType(const TypedefNameDecl *Decl,
                           QualType Underlying = QualType()) const;
 
   QualType getRecordType(const RecordDecl *Decl) const;
 
   QualType getEnumType(const EnumDecl *Decl) const;
 
   /// Compute BestType and BestPromotionType for an enum based on the highest
   /// number of negative and positive bits of its elements.
   /// Returns true if enum width is too large.
   bool computeBestEnumTypes(bool IsPacked, unsigned NumNegativeBits,
                             unsigned NumPositiveBits, QualType &BestType,
                             QualType &BestPromotionType);
 
   QualType
   getUnresolvedUsingType(const UnresolvedUsingTypenameDecl *Decl) const;
 
   QualType getInjectedClassNameType(CXXRecordDecl *Decl, QualType TST) const;
 
   QualType getAttributedType(attr::Kind attrKind, QualType modifiedType,
                              QualType equivalentType,
                              const Attr *attr = nullptr) const;
 
   QualType getAttributedType(const Attr *attr, QualType modifiedType,
                              QualType equivalentType) const;
 
   QualType getAttributedType(NullabilityKind nullability, QualType modifiedType,
                              QualType equivalentType);
 
   QualType getBTFTagAttributedType(const BTFTypeTagAttr *BTFAttr,
                                    QualType Wrapped) const;
 
   QualType getHLSLAttributedResourceType(
       QualType Wrapped, QualType Contained,
       const HLSLAttributedResourceType::Attributes &Attrs);
 
   QualType
   getSubstTemplateTypeParmType(QualType Replacement, Decl *AssociatedDecl,
                                unsigned Index,
                                std::optional<unsigned> PackIndex,
                                SubstTemplateTypeParmTypeFlag Flag =
                                    SubstTemplateTypeParmTypeFlag::None) const;
   QualType getSubstTemplateTypeParmPackType(Decl *AssociatedDecl,
                                             unsigned Index, bool Final,
                                             const TemplateArgument &ArgPack);
 
   QualType
   getTemplateTypeParmType(unsigned Depth, unsigned Index,
                           bool ParameterPack,
                           TemplateTypeParmDecl *ParmDecl = nullptr) const;
 
   QualType getTemplateSpecializationType(TemplateName T,
                                          ArrayRef<TemplateArgument> Args,
                                          QualType Canon = QualType()) const;
 
   QualType
   getCanonicalTemplateSpecializationType(TemplateName T,
                                          ArrayRef<TemplateArgument> Args) const;
 
   QualType getTemplateSpecializationType(TemplateName T,
                                          ArrayRef<TemplateArgumentLoc> Args,
                                          QualType Canon = QualType()) const;
 
   TypeSourceInfo *
   getTemplateSpecializationTypeInfo(TemplateName T, SourceLocation TLoc,
                                     const TemplateArgumentListInfo &Args,
                                     QualType Canon = QualType()) const;
 
   QualType getParenType(QualType NamedType) const;
 
   QualType getMacroQualifiedType(QualType UnderlyingTy,
                                  const IdentifierInfo *MacroII) const;
 
   QualType getElaboratedType(ElaboratedTypeKeyword Keyword,
                              NestedNameSpecifier *NNS, QualType NamedType,
                              TagDecl *OwnedTagDecl = nullptr) const;
   QualType getDependentNameType(ElaboratedTypeKeyword Keyword,
                                 NestedNameSpecifier *NNS,
                                 const IdentifierInfo *Name,
                                 QualType Canon = QualType()) const;
 
   QualType getDependentTemplateSpecializationType(
       ElaboratedTypeKeyword Keyword, NestedNameSpecifier *NNS,
       const IdentifierInfo *Name, ArrayRef<TemplateArgumentLoc> Args) const;
   QualType getDependentTemplateSpecializationType(
       ElaboratedTypeKeyword Keyword, NestedNameSpecifier *NNS,
       const IdentifierInfo *Name, ArrayRef<TemplateArgument> Args) const;
 
   TemplateArgument getInjectedTemplateArg(NamedDecl *ParamDecl) const;
 
   /// Form a pack expansion type with the given pattern.
   /// \param NumExpansions The number of expansions for the pack, if known.
   /// \param ExpectPackInType If \c false, we should not expect \p Pattern to
   ///        contain an unexpanded pack. This only makes sense if the pack
   ///        expansion is used in a context where the arity is inferred from
   ///        elsewhere, such as if the pattern contains a placeholder type or
   ///        if this is the canonical type of another pack expansion type.
   QualType getPackExpansionType(QualType Pattern,
                                 std::optional<unsigned> NumExpansions,
                                 bool ExpectPackInType = true) const;
 
   QualType getObjCInterfaceType(const ObjCInterfaceDecl *Decl,
                                 ObjCInterfaceDecl *PrevDecl = nullptr) const;
 
   /// Legacy interface: cannot provide type arguments or __kindof.
   QualType getObjCObjectType(QualType Base,
                              ObjCProtocolDecl * const *Protocols,
                              unsigned NumProtocols) const;
 
   QualType getObjCObjectType(QualType Base,
                              ArrayRef<QualType> typeArgs,
                              ArrayRef<ObjCProtocolDecl *> protocols,
                              bool isKindOf) const;
 
   QualType getObjCTypeParamType(const ObjCTypeParamDecl *Decl,
                                 ArrayRef<ObjCProtocolDecl *> protocols) const;
   void adjustObjCTypeParamBoundType(const ObjCTypeParamDecl *Orig,
                                     ObjCTypeParamDecl *New) const;
 
   bool ObjCObjectAdoptsQTypeProtocols(QualType QT, ObjCInterfaceDecl *Decl);
 
   /// QIdProtocolsAdoptObjCObjectProtocols - Checks that protocols in
   /// QT's qualified-id protocol list adopt all protocols in IDecl's list
   /// of protocols.
   bool QIdProtocolsAdoptObjCObjectProtocols(QualType QT,
                                             ObjCInterfaceDecl *IDecl);
 
   /// Return a ObjCObjectPointerType type for the given ObjCObjectType.
   QualType getObjCObjectPointerType(QualType OIT) const;
 
   /// C23 feature and GCC extension.
   QualType getTypeOfExprType(Expr *E, TypeOfKind Kind) const;
   QualType getTypeOfType(QualType QT, TypeOfKind Kind) const;
 
   QualType getReferenceQualifiedType(const Expr *e) const;
 
   /// C++11 decltype.
   QualType getDecltypeType(Expr *e, QualType UnderlyingType) const;
 
   QualType getPackIndexingType(QualType Pattern, Expr *IndexExpr,
                                bool FullySubstituted = false,
                                ArrayRef<QualType> Expansions = {},
                                int Index = -1) const;
 
   /// Unary type transforms
   QualType getUnaryTransformType(QualType BaseType, QualType UnderlyingType,
                                  UnaryTransformType::UTTKind UKind) const;
 
   /// C++11 deduced auto type.
   QualType getAutoType(QualType DeducedType, AutoTypeKeyword Keyword,
                        bool IsDependent, bool IsPack = false,
                        ConceptDecl *TypeConstraintConcept = nullptr,
                        ArrayRef<TemplateArgument> TypeConstraintArgs ={}) const;
 
   /// C++11 deduction pattern for 'auto' type.
   QualType getAutoDeductType() const;
 
   /// C++11 deduction pattern for 'auto &&' type.
   QualType getAutoRRefDeductType() const;
 
   /// Remove any type constraints from a template parameter type, for
   /// equivalence comparison of template parameters.
   QualType getUnconstrainedType(QualType T) const;
 
   /// C++17 deduced class template specialization type.
   QualType getDeducedTemplateSpecializationType(TemplateName Template,
                                                 QualType DeducedType,
                                                 bool IsDependent) const;
 
 private:
   QualType getDeducedTemplateSpecializationTypeInternal(TemplateName Template,
                                                         QualType DeducedType,
                                                         bool IsDependent,
                                                         QualType Canon) const;
 
 public:
   /// Return the unique reference to the type for the specified TagDecl
   /// (struct/union/class/enum) decl.
   QualType getTagDeclType(const TagDecl *Decl) const;
 
   /// Return the unique type for "size_t" (C99 7.17), defined in
   /// <stddef.h>.
   ///
   /// The sizeof operator requires this (C99 6.5.3.4p4).
   CanQualType getSizeType() const;
 
   /// Return the unique signed counterpart of
   /// the integer type corresponding to size_t.
   CanQualType getSignedSizeType() const;
 
   /// Return the unique type for "intmax_t" (C99 7.18.1.5), defined in
   /// <stdint.h>.
   CanQualType getIntMaxType() const;
 
   /// Return the unique type for "uintmax_t" (C99 7.18.1.5), defined in
   /// <stdint.h>.
   CanQualType getUIntMaxType() const;
 
   /// Return the unique wchar_t type available in C++ (and available as
   /// __wchar_t as a Microsoft extension).
   QualType getWCharType() const { return WCharTy; }
 
   /// Return the type of wide characters. In C++, this returns the
   /// unique wchar_t type. In C99, this returns a type compatible with the type
   /// defined in <stddef.h> as defined by the target.
   QualType getWideCharType() const { return WideCharTy; }
 
   /// Return the type of "signed wchar_t".
   ///
   /// Used when in C++, as a GCC extension.
   QualType getSignedWCharType() const;
 
   /// Return the type of "unsigned wchar_t".
   ///
   /// Used when in C++, as a GCC extension.
   QualType getUnsignedWCharType() const;
 
   /// In C99, this returns a type compatible with the type
   /// defined in <stddef.h> as defined by the target.
   QualType getWIntType() const { return WIntTy; }
 
   /// Return a type compatible with "intptr_t" (C99 7.18.1.4),
   /// as defined by the target.
   QualType getIntPtrType() const;
 
   /// Return a type compatible with "uintptr_t" (C99 7.18.1.4),
   /// as defined by the target.
   QualType getUIntPtrType() const;
 
   /// Return the unique type for "ptrdiff_t" (C99 7.17) defined in
   /// <stddef.h>. Pointer - pointer requires this (C99 6.5.6p9).
   QualType getPointerDiffType() const;
 
   /// Return the unique unsigned counterpart of "ptrdiff_t"
   /// integer type. The standard (C11 7.21.6.1p7) refers to this type
   /// in the definition of %tu format specifier.
   QualType getUnsignedPointerDiffType() const;
 
   /// Return the unique type for "pid_t" defined in
   /// <sys/types.h>. We need this to compute the correct type for vfork().
   QualType getProcessIDType() const;
 
   /// Return the C structure type used to represent constant CFStrings.
   QualType getCFConstantStringType() const;
 
   /// Returns the C struct type for objc_super
   QualType getObjCSuperType() const;
   void setObjCSuperType(QualType ST) { ObjCSuperType = ST; }
 
   /// Get the structure type used to representation CFStrings, or NULL
   /// if it hasn't yet been built.
   QualType getRawCFConstantStringType() const {
     if (CFConstantStringTypeDecl)
       return getTypedefType(CFConstantStringTypeDecl);
     return QualType();
   }
   void setCFConstantStringType(QualType T);
   TypedefDecl *getCFConstantStringDecl() const;
   RecordDecl *getCFConstantStringTagDecl() const;
 
   // This setter/getter represents the ObjC type for an NSConstantString.
   void setObjCConstantStringInterface(ObjCInterfaceDecl *Decl);
   QualType getObjCConstantStringInterface() const {
     return ObjCConstantStringType;
   }
 
   QualType getObjCNSStringType() const {
     return ObjCNSStringType;
   }
 
   void setObjCNSStringType(QualType T) {
     ObjCNSStringType = T;
   }
 
   /// Retrieve the type that \c id has been defined to, which may be
   /// different from the built-in \c id if \c id has been typedef'd.
   QualType getObjCIdRedefinitionType() const {
     if (ObjCIdRedefinitionType.isNull())
       return getObjCIdType();
     return ObjCIdRedefinitionType;
   }
 
   /// Set the user-written type that redefines \c id.
   void setObjCIdRedefinitionType(QualType RedefType) {
     ObjCIdRedefinitionType = RedefType;
   }
 
   /// Retrieve the type that \c Class has been defined to, which may be
   /// different from the built-in \c Class if \c Class has been typedef'd.
   QualType getObjCClassRedefinitionType() const {
     if (ObjCClassRedefinitionType.isNull())
       return getObjCClassType();
     return ObjCClassRedefinitionType;
   }
 
   /// Set the user-written type that redefines 'SEL'.
   void setObjCClassRedefinitionType(QualType RedefType) {
     ObjCClassRedefinitionType = RedefType;
   }
 
   /// Retrieve the type that 'SEL' has been defined to, which may be
   /// different from the built-in 'SEL' if 'SEL' has been typedef'd.
   QualType getObjCSelRedefinitionType() const {
     if (ObjCSelRedefinitionType.isNull())
       return getObjCSelType();
     return ObjCSelRedefinitionType;
   }
 
   /// Set the user-written type that redefines 'SEL'.
   void setObjCSelRedefinitionType(QualType RedefType) {
     ObjCSelRedefinitionType = RedefType;
   }
 
   /// Retrieve the identifier 'NSObject'.
   IdentifierInfo *getNSObjectName() const {
     if (!NSObjectName) {
       NSObjectName = &Idents.get("NSObject");
     }
 
     return NSObjectName;
   }
 
   /// Retrieve the identifier 'NSCopying'.
   IdentifierInfo *getNSCopyingName() {
     if (!NSCopyingName) {
       NSCopyingName = &Idents.get("NSCopying");
     }
 
     return NSCopyingName;
   }
 
   CanQualType getNSUIntegerType() const;
 
   CanQualType getNSIntegerType() const;
 
   /// Retrieve the identifier 'bool'.
   IdentifierInfo *getBoolName() const {
     if (!BoolName)
       BoolName = &Idents.get("bool");
     return BoolName;
   }
 
   IdentifierInfo *getMakeIntegerSeqName() const {
     if (!MakeIntegerSeqName)
       MakeIntegerSeqName = &Idents.get("__make_integer_seq");
     return MakeIntegerSeqName;
   }
 
   IdentifierInfo *getTypePackElementName() const {
     if (!TypePackElementName)
       TypePackElementName = &Idents.get("__type_pack_element");
     return TypePackElementName;
   }
 
   IdentifierInfo *getBuiltinCommonTypeName() const {
     if (!BuiltinCommonTypeName)
       BuiltinCommonTypeName = &Idents.get("__builtin_common_type");
     return BuiltinCommonTypeName;
   }
 
   /// Retrieve the Objective-C "instancetype" type, if already known;
   /// otherwise, returns a NULL type;
   QualType getObjCInstanceType() {
     return getTypeDeclType(getObjCInstanceTypeDecl());
   }
 
   /// Retrieve the typedef declaration corresponding to the Objective-C
   /// "instancetype" type.
   TypedefDecl *getObjCInstanceTypeDecl();
 
   /// Set the type for the C FILE type.
   void setFILEDecl(TypeDecl *FILEDecl) { this->FILEDecl = FILEDecl; }
 
   /// Retrieve the C FILE type.
   QualType getFILEType() const {
     if (FILEDecl)
       return getTypeDeclType(FILEDecl);
     return QualType();
   }
 
   /// Set the type for the C jmp_buf type.
   void setjmp_bufDecl(TypeDecl *jmp_bufDecl) {
     this->jmp_bufDecl = jmp_bufDecl;
   }
 
   /// Retrieve the C jmp_buf type.
   QualType getjmp_bufType() const {
     if (jmp_bufDecl)
       return getTypeDeclType(jmp_bufDecl);
     return QualType();
   }
 
   /// Set the type for the C sigjmp_buf type.
   void setsigjmp_bufDecl(TypeDecl *sigjmp_bufDecl) {
     this->sigjmp_bufDecl = sigjmp_bufDecl;
   }
 
   /// Retrieve the C sigjmp_buf type.
   QualType getsigjmp_bufType() const {
     if (sigjmp_bufDecl)
       return getTypeDeclType(sigjmp_bufDecl);
     return QualType();
   }
 
   /// Set the type for the C ucontext_t type.
   void setucontext_tDecl(TypeDecl *ucontext_tDecl) {
     this->ucontext_tDecl = ucontext_tDecl;
   }
 
   /// Retrieve the C ucontext_t type.
   QualType getucontext_tType() const {
     if (ucontext_tDecl)
       return getTypeDeclType(ucontext_tDecl);
     return QualType();
   }
 
   /// The result type of logical operations, '<', '>', '!=', etc.
   QualType getLogicalOperationType() const {
     return getLangOpts().CPlusPlus ? BoolTy : IntTy;
   }
 
   /// Emit the Objective-CC type encoding for the given type \p T into
   /// \p S.
   ///
   /// If \p Field is specified then record field names are also encoded.
   void getObjCEncodingForType(QualType T, std::string &S,
                               const FieldDecl *Field=nullptr,
                               QualType *NotEncodedT=nullptr) const;
 
   /// Emit the Objective-C property type encoding for the given
   /// type \p T into \p S.
   void getObjCEncodingForPropertyType(QualType T, std::string &S) const;
 
   void getLegacyIntegralTypeEncoding(QualType &t) const;
 
   /// Put the string version of the type qualifiers \p QT into \p S.
   void getObjCEncodingForTypeQualifier(Decl::ObjCDeclQualifier QT,
                                        std::string &S) const;
 
   /// Emit the encoded type for the function \p Decl into \p S.
   ///
   /// This is in the same format as Objective-C method encodings.
   ///
   /// \returns true if an error occurred (e.g., because one of the parameter
   /// types is incomplete), false otherwise.
   std::string getObjCEncodingForFunctionDecl(const FunctionDecl *Decl) const;
 
   /// Emit the encoded type for the method declaration \p Decl into
   /// \p S.
   std::string getObjCEncodingForMethodDecl(const ObjCMethodDecl *Decl,
                                            bool Extended = false) const;
 
   /// Return the encoded type for this block declaration.
   std::string getObjCEncodingForBlock(const BlockExpr *blockExpr) const;
 
   /// getObjCEncodingForPropertyDecl - Return the encoded type for
   /// this method declaration. If non-NULL, Container must be either
   /// an ObjCCategoryImplDecl or ObjCImplementationDecl; it should
   /// only be NULL when getting encodings for protocol properties.
   std::string getObjCEncodingForPropertyDecl(const ObjCPropertyDecl *PD,
                                              const Decl *Container) const;
 
   bool ProtocolCompatibleWithProtocol(ObjCProtocolDecl *lProto,
                                       ObjCProtocolDecl *rProto) const;
 
   ObjCPropertyImplDecl *getObjCPropertyImplDeclForPropertyDecl(
                                                   const ObjCPropertyDecl *PD,
                                                   const Decl *Container) const;
 
   /// Return the size of type \p T for Objective-C encoding purpose,
   /// in characters.
   CharUnits getObjCEncodingTypeSize(QualType T) const;
 
   /// Retrieve the typedef corresponding to the predefined \c id type
   /// in Objective-C.
   TypedefDecl *getObjCIdDecl() const;
 
   /// Represents the Objective-CC \c id type.
   ///
   /// This is set up lazily, by Sema.  \c id is always a (typedef for a)
   /// pointer type, a pointer to a struct.
   QualType getObjCIdType() const {
     return getTypeDeclType(getObjCIdDecl());
   }
 
   /// Retrieve the typedef corresponding to the predefined 'SEL' type
   /// in Objective-C.
   TypedefDecl *getObjCSelDecl() const;
 
   /// Retrieve the type that corresponds to the predefined Objective-C
   /// 'SEL' type.
   QualType getObjCSelType() const {
     return getTypeDeclType(getObjCSelDecl());
   }
 
   /// Retrieve the typedef declaration corresponding to the predefined
   /// Objective-C 'Class' type.
   TypedefDecl *getObjCClassDecl() const;
 
   /// Represents the Objective-C \c Class type.
   ///
   /// This is set up lazily, by Sema.  \c Class is always a (typedef for a)
   /// pointer type, a pointer to a struct.
   QualType getObjCClassType() const {
     return getTypeDeclType(getObjCClassDecl());
   }
 
   /// Retrieve the Objective-C class declaration corresponding to
   /// the predefined \c Protocol class.
   ObjCInterfaceDecl *getObjCProtocolDecl() const;
 
   /// Retrieve declaration of 'BOOL' typedef
   TypedefDecl *getBOOLDecl() const {
     return BOOLDecl;
   }
 
   /// Save declaration of 'BOOL' typedef
   void setBOOLDecl(TypedefDecl *TD) {
     BOOLDecl = TD;
   }
 
   /// type of 'BOOL' type.
   QualType getBOOLType() const {
     return getTypeDeclType(getBOOLDecl());
   }
 
   /// Retrieve the type of the Objective-C \c Protocol class.
   QualType getObjCProtoType() const {
     return getObjCInterfaceType(getObjCProtocolDecl());
   }
 
   /// Retrieve the C type declaration corresponding to the predefined
   /// \c __builtin_va_list type.
   TypedefDecl *getBuiltinVaListDecl() const;
 
   /// Retrieve the type of the \c __builtin_va_list type.
   QualType getBuiltinVaListType() const {
     return getTypeDeclType(getBuiltinVaListDecl());
   }
 
   /// Retrieve the C type declaration corresponding to the predefined
   /// \c __va_list_tag type used to help define the \c __builtin_va_list type
   /// for some targets.
   Decl *getVaListTagDecl() const;
 
   /// Retrieve the C type declaration corresponding to the predefined
   /// \c __builtin_ms_va_list type.
   TypedefDecl *getBuiltinMSVaListDecl() const;
 
   /// Retrieve the type of the \c __builtin_ms_va_list type.
   QualType getBuiltinMSVaListType() const {
     return getTypeDeclType(getBuiltinMSVaListDecl());
   }
 
   /// Retrieve the implicitly-predeclared 'struct _GUID' declaration.
   TagDecl *getMSGuidTagDecl() const { return MSGuidTagDecl; }
 
   /// Retrieve the implicitly-predeclared 'struct _GUID' type.
   QualType getMSGuidType() const {
     assert(MSGuidTagDecl && "asked for GUID type but MS extensions disabled");
     return getTagDeclType(MSGuidTagDecl);
   }
 
   /// Return whether a declaration to a builtin is allowed to be
   /// overloaded/redeclared.
   bool canBuiltinBeRedeclared(const FunctionDecl *) const;
 
   /// Return a type with additional \c const, \c volatile, or
   /// \c restrict qualifiers.
   QualType getCVRQualifiedType(QualType T, unsigned CVR) const {
     return getQualifiedType(T, Qualifiers::fromCVRMask(CVR));
   }
 
   /// Un-split a SplitQualType.
   QualType getQualifiedType(SplitQualType split) const {
     return getQualifiedType(split.Ty, split.Quals);
   }
 
   /// Return a type with additional qualifiers.
   QualType getQualifiedType(QualType T, Qualifiers Qs) const {
     if (!Qs.hasNonFastQualifiers())
       return T.withFastQualifiers(Qs.getFastQualifiers());
     QualifierCollector Qc(Qs);
     const Type *Ptr = Qc.strip(T);
     return getExtQualType(Ptr, Qc);
   }
 
   /// Return a type with additional qualifiers.
   QualType getQualifiedType(const Type *T, Qualifiers Qs) const {
     if (!Qs.hasNonFastQualifiers())
       return QualType(T, Qs.getFastQualifiers());
     return getExtQualType(T, Qs);
   }
 
   /// Return a type with the given lifetime qualifier.
   ///
   /// \pre Neither type.ObjCLifetime() nor \p lifetime may be \c OCL_None.
   QualType getLifetimeQualifiedType(QualType type,
                                     Qualifiers::ObjCLifetime lifetime) {
     assert(type.getObjCLifetime() == Qualifiers::OCL_None);
     assert(lifetime != Qualifiers::OCL_None);
 
     Qualifiers qs;
     qs.addObjCLifetime(lifetime);
     return getQualifiedType(type, qs);
   }
 
   /// getUnqualifiedObjCPointerType - Returns version of
   /// Objective-C pointer type with lifetime qualifier removed.
   QualType getUnqualifiedObjCPointerType(QualType type) const {
     if (!type.getTypePtr()->isObjCObjectPointerType() ||
         !type.getQualifiers().hasObjCLifetime())
       return type;
     Qualifiers Qs = type.getQualifiers();
     Qs.removeObjCLifetime();
     return getQualifiedType(type.getUnqualifiedType(), Qs);
   }
 
   /// \brief Return a type with the given __ptrauth qualifier.
   QualType getPointerAuthType(QualType Ty, PointerAuthQualifier PointerAuth) {
     assert(!Ty.getPointerAuth());
     assert(PointerAuth);
 
     Qualifiers Qs;
     Qs.setPointerAuth(PointerAuth);
     return getQualifiedType(Ty, Qs);
   }
 
   unsigned char getFixedPointScale(QualType Ty) const;
   unsigned char getFixedPointIBits(QualType Ty) const;
   llvm::FixedPointSemantics getFixedPointSemantics(QualType Ty) const;
   llvm::APFixedPoint getFixedPointMax(QualType Ty) const;
   llvm::APFixedPoint getFixedPointMin(QualType Ty) const;
 
   DeclarationNameInfo getNameForTemplate(TemplateName Name,
                                          SourceLocation NameLoc) const;
 
   TemplateName getOverloadedTemplateName(UnresolvedSetIterator Begin,
                                          UnresolvedSetIterator End) const;
   TemplateName getAssumedTemplateName(DeclarationName Name) const;
 
   TemplateName getQualifiedTemplateName(NestedNameSpecifier *NNS,
                                         bool TemplateKeyword,
                                         TemplateName Template) const;
 
   TemplateName getDependentTemplateName(NestedNameSpecifier *NNS,
                                         const IdentifierInfo *Name) const;
   TemplateName getDependentTemplateName(NestedNameSpecifier *NNS,
                                         OverloadedOperatorKind Operator) const;
   TemplateName
   getSubstTemplateTemplateParm(TemplateName replacement, Decl *AssociatedDecl,
                                unsigned Index,
                                std::optional<unsigned> PackIndex) const;
   TemplateName getSubstTemplateTemplateParmPack(const TemplateArgument &ArgPack,
                                                 Decl *AssociatedDecl,
                                                 unsigned Index,
                                                 bool Final) const;
 
   /// Represents a TemplateName which had some of its default arguments
   /// deduced. This both represents this default argument deduction as sugar,
   /// and provides the support for it's equivalences through canonicalization.
   /// For example DeducedTemplateNames which have the same set of default
   /// arguments are equivalent, and are also equivalent to the underlying
   /// template when the deduced template arguments are the same.
   TemplateName getDeducedTemplateName(TemplateName Underlying,
                                       DefaultArguments DefaultArgs) const;
 
   enum GetBuiltinTypeError {
     /// No error
     GE_None,
 
     /// Missing a type
     GE_Missing_type,
 
     /// Missing a type from <stdio.h>
     GE_Missing_stdio,
 
     /// Missing a type from <setjmp.h>
     GE_Missing_setjmp,
 
     /// Missing a type from <ucontext.h>
     GE_Missing_ucontext
   };
 
   QualType DecodeTypeStr(const char *&Str, const ASTContext &Context,
                          ASTContext::GetBuiltinTypeError &Error,
                          bool &RequireICE, bool AllowTypeModifiers) const;
 
   /// Return the type for the specified builtin.
   ///
   /// If \p IntegerConstantArgs is non-null, it is filled in with a bitmask of
   /// arguments to the builtin that are required to be integer constant
   /// expressions.
   QualType GetBuiltinType(unsigned ID, GetBuiltinTypeError &Error,
                           unsigned *IntegerConstantArgs = nullptr) const;
 
   /// Types and expressions required to build C++2a three-way comparisons
   /// using operator<=>, including the values return by builtin <=> operators.
   ComparisonCategories CompCategories;
 
 private:
   CanQualType getFromTargetType(unsigned Type) const;
   TypeInfo getTypeInfoImpl(const Type *T) const;
 
   //===--------------------------------------------------------------------===//
   //                         Type Predicates.
   //===--------------------------------------------------------------------===//
 
 public:
   /// Return one of the GCNone, Weak or Strong Objective-C garbage
   /// collection attributes.
   Qualifiers::GC getObjCGCAttrKind(QualType Ty) const;
 
   /// Return true if the given vector types are of the same unqualified
   /// type or if they are equivalent to the same GCC vector type.
   ///
   /// \note This ignores whether they are target-specific (AltiVec or Neon)
   /// types.
   bool areCompatibleVectorTypes(QualType FirstVec, QualType SecondVec);
 
   /// Return true if the given types are an SVE builtin and a VectorType that
   /// is a fixed-length representation of the SVE builtin for a specific
   /// vector-length.
   bool areCompatibleSveTypes(QualType FirstType, QualType SecondType);
 
   /// Return true if the given vector types are lax-compatible SVE vector types,
   /// false otherwise.
   bool areLaxCompatibleSveTypes(QualType FirstType, QualType SecondType);
 
   /// Return true if the given types are an RISC-V vector builtin type and a
   /// VectorType that is a fixed-length representation of the RISC-V vector
   /// builtin type for a specific vector-length.
   bool areCompatibleRVVTypes(QualType FirstType, QualType SecondType);
 
   /// Return true if the given vector types are lax-compatible RISC-V vector
   /// types as defined by -flax-vector-conversions=, which permits implicit
   /// conversions between vectors with different number of elements and/or
   /// incompatible element types, false otherwise.
   bool areLaxCompatibleRVVTypes(QualType FirstType, QualType SecondType);
 
   /// Return true if the type has been explicitly qualified with ObjC ownership.
   /// A type may be implicitly qualified with ownership under ObjC ARC, and in
   /// some cases the compiler treats these differently.
   bool hasDirectOwnershipQualifier(QualType Ty) const;
 
   /// Return true if this is an \c NSObject object with its \c NSObject
   /// attribute set.
   static bool isObjCNSObjectType(QualType Ty) {
     return Ty->isObjCNSObjectType();
   }
 
   //===--------------------------------------------------------------------===//
   //                         Type Sizing and Analysis
   //===--------------------------------------------------------------------===//
 
   /// Return the APFloat 'semantics' for the specified scalar floating
   /// point type.
   const llvm::fltSemantics &getFloatTypeSemantics(QualType T) const;
 
   /// Get the size and alignment of the specified complete type in bits.
   TypeInfo getTypeInfo(const Type *T) const;
   TypeInfo getTypeInfo(QualType T) const { return getTypeInfo(T.getTypePtr()); }
 
   /// Get default simd alignment of the specified complete type in bits.
   unsigned getOpenMPDefaultSimdAlign(QualType T) const;
 
   /// Return the size of the specified (complete) type \p T, in bits.
   uint64_t getTypeSize(QualType T) const { return getTypeInfo(T).Width; }
   uint64_t getTypeSize(const Type *T) const { return getTypeInfo(T).Width; }
 
   /// Return the size of the character type, in bits.
   uint64_t getCharWidth() const {
     return getTypeSize(CharTy);
   }
 
   /// Convert a size in bits to a size in characters.
   CharUnits toCharUnitsFromBits(int64_t BitSize) const;
 
   /// Convert a size in characters to a size in bits.
   int64_t toBits(CharUnits CharSize) const;
 
   /// Return the size of the specified (complete) type \p T, in
   /// characters.
   CharUnits getTypeSizeInChars(QualType T) const;
   CharUnits getTypeSizeInChars(const Type *T) const;
 
   std::optional<CharUnits> getTypeSizeInCharsIfKnown(QualType Ty) const {
     if (Ty->isIncompleteType() || Ty->isDependentType())
       return std::nullopt;
     return getTypeSizeInChars(Ty);
   }
 
   std::optional<CharUnits> getTypeSizeInCharsIfKnown(const Type *Ty) const {
     return getTypeSizeInCharsIfKnown(QualType(Ty, 0));
   }
 
   /// Return the ABI-specified alignment of a (complete) type \p T, in
   /// bits.
   unsigned getTypeAlign(QualType T) const { return getTypeInfo(T).Align; }
   unsigned getTypeAlign(const Type *T) const { return getTypeInfo(T).Align; }
 
   /// Return the ABI-specified natural alignment of a (complete) type \p T,
   /// before alignment adjustments, in bits.
   ///
   /// This alignment is curently used only by ARM and AArch64 when passing
   /// arguments of a composite type.
   unsigned getTypeUnadjustedAlign(QualType T) const {
     return getTypeUnadjustedAlign(T.getTypePtr());
   }
   unsigned getTypeUnadjustedAlign(const Type *T) const;
 
   /// Return the alignment of a type, in bits, or 0 if
   /// the type is incomplete and we cannot determine the alignment (for
   /// example, from alignment attributes). The returned alignment is the
   /// Preferred alignment if NeedsPreferredAlignment is true, otherwise is the
   /// ABI alignment.
   unsigned getTypeAlignIfKnown(QualType T,
                                bool NeedsPreferredAlignment = false) const;
 
   /// Return the ABI-specified alignment of a (complete) type \p T, in
   /// characters.
   CharUnits getTypeAlignInChars(QualType T) const;
   CharUnits getTypeAlignInChars(const Type *T) const;
 
   /// Return the PreferredAlignment of a (complete) type \p T, in
   /// characters.
   CharUnits getPreferredTypeAlignInChars(QualType T) const {
     return toCharUnitsFromBits(getPreferredTypeAlign(T));
   }
 
   /// getTypeUnadjustedAlignInChars - Return the ABI-specified alignment of a type,
   /// in characters, before alignment adjustments. This method does not work on
   /// incomplete types.
   CharUnits getTypeUnadjustedAlignInChars(QualType T) const;
   CharUnits getTypeUnadjustedAlignInChars(const Type *T) const;
 
   // getTypeInfoDataSizeInChars - Return the size of a type, in chars. If the
   // type is a record, its data size is returned.
   TypeInfoChars getTypeInfoDataSizeInChars(QualType T) const;
 
   TypeInfoChars getTypeInfoInChars(const Type *T) const;
   TypeInfoChars getTypeInfoInChars(QualType T) const;
 
   /// Determine if the alignment the type has was required using an
   /// alignment attribute.
   bool isAlignmentRequired(const Type *T) const;
   bool isAlignmentRequired(QualType T) const;
 
   /// More type predicates useful for type checking/promotion
   bool isPromotableIntegerType(QualType T) const; // C99 6.3.1.1p2
 
   /// Return the "preferred" alignment of the specified type \p T for
   /// the current target, in bits.
   ///
   /// This can be different than the ABI alignment in cases where it is
   /// beneficial for performance or backwards compatibility preserving to
   /// overalign a data type. (Note: despite the name, the preferred alignment
   /// is ABI-impacting, and not an optimization.)
   unsigned getPreferredTypeAlign(QualType T) const {
     return getPreferredTypeAlign(T.getTypePtr());
   }
   unsigned getPreferredTypeAlign(const Type *T) const;
 
   /// Return the default alignment for __attribute__((aligned)) on
   /// this target, to be used if no alignment value is specified.
   unsigned getTargetDefaultAlignForAttributeAligned() const;
 
   /// Return the alignment in bits that should be given to a
   /// global variable with type \p T. If \p VD is non-null it will be
   /// considered specifically for the query.
   unsigned getAlignOfGlobalVar(QualType T, const VarDecl *VD) const;
 
   /// Return the alignment in characters that should be given to a
   /// global variable with type \p T. If \p VD is non-null it will be
   /// considered specifically for the query.
   CharUnits getAlignOfGlobalVarInChars(QualType T, const VarDecl *VD) const;
 
   /// Return the minimum alignement as specified by the target. If \p VD is
   /// non-null it may be used to identify external or weak variables.
   unsigned getMinGlobalAlignOfVar(uint64_t Size, const VarDecl *VD) const;
 
   /// Return a conservative estimate of the alignment of the specified
   /// decl \p D.
   ///
   /// \pre \p D must not be a bitfield type, as bitfields do not have a valid
   /// alignment.
   ///
   /// If \p ForAlignof, references are treated like their underlying type
   /// and  large arrays don't get any special treatment. If not \p ForAlignof
   /// it computes the value expected by CodeGen: references are treated like
   /// pointers and large arrays get extra alignment.
   CharUnits getDeclAlign(const Decl *D, bool ForAlignof = false) const;
 
   /// Return the alignment (in bytes) of the thrown exception object. This is
   /// only meaningful for targets that allocate C++ exceptions in a system
   /// runtime, such as those using the Itanium C++ ABI.
   CharUnits getExnObjectAlignment() const;
 
   /// Get or compute information about the layout of the specified
   /// record (struct/union/class) \p D, which indicates its size and field
   /// position information.
   const ASTRecordLayout &getASTRecordLayout(const RecordDecl *D) const;
 
   /// Get or compute information about the layout of the specified
   /// Objective-C interface.
   const ASTRecordLayout &getASTObjCInterfaceLayout(const ObjCInterfaceDecl *D)
     const;
 
   void DumpRecordLayout(const RecordDecl *RD, raw_ostream &OS,
                         bool Simple = false) const;
 
   /// Get or compute information about the layout of the specified
   /// Objective-C implementation.
   ///
   /// This may differ from the interface if synthesized ivars are present.
   const ASTRecordLayout &
   getASTObjCImplementationLayout(const ObjCImplementationDecl *D) const;
 
   /// Get our current best idea for the key function of the
   /// given record decl, or nullptr if there isn't one.
   ///
   /// The key function is, according to the Itanium C++ ABI section 5.2.3:
   ///   ...the first non-pure virtual function that is not inline at the
   ///   point of class definition.
   ///
   /// Other ABIs use the same idea.  However, the ARM C++ ABI ignores
   /// virtual functions that are defined 'inline', which means that
   /// the result of this computation can change.
   const CXXMethodDecl *getCurrentKeyFunction(const CXXRecordDecl *RD);
 
   /// Observe that the given method cannot be a key function.
   /// Checks the key-function cache for the method's class and clears it
   /// if matches the given declaration.
   ///
   /// This is used in ABIs where out-of-line definitions marked
   /// inline are not considered to be key functions.
   ///
   /// \param method should be the declaration from the class definition
   void setNonKeyFunction(const CXXMethodDecl *method);
 
   /// Loading virtual member pointers using the virtual inheritance model
   /// always results in an adjustment using the vbtable even if the index is
   /// zero.
   ///
   /// This is usually OK because the first slot in the vbtable points
   /// backwards to the top of the MDC.  However, the MDC might be reusing a
   /// vbptr from an nv-base.  In this case, the first slot in the vbtable
   /// points to the start of the nv-base which introduced the vbptr and *not*
   /// the MDC.  Modify the NonVirtualBaseAdjustment to account for this.
   CharUnits getOffsetOfBaseWithVBPtr(const CXXRecordDecl *RD) const;
 
   /// Get the offset of a FieldDecl or IndirectFieldDecl, in bits.
   uint64_t getFieldOffset(const ValueDecl *FD) const;
 
   /// Get the offset of an ObjCIvarDecl in bits.
   uint64_t lookupFieldBitOffset(const ObjCInterfaceDecl *OID,
                                 const ObjCImplementationDecl *ID,
                                 const ObjCIvarDecl *Ivar) const;
 
   /// Find the 'this' offset for the member path in a pointer-to-member
   /// APValue.
   CharUnits getMemberPointerPathAdjustment(const APValue &MP) const;
 
   bool isNearlyEmpty(const CXXRecordDecl *RD) const;
 
   VTableContextBase *getVTableContext();
 
   /// If \p T is null pointer, assume the target in ASTContext.
   MangleContext *createMangleContext(const TargetInfo *T = nullptr);
 
   /// Creates a device mangle context to correctly mangle lambdas in a mixed
   /// architecture compile by setting the lambda mangling number source to the
   /// DeviceLambdaManglingNumber. Currently this asserts that the TargetInfo
   /// (from the AuxTargetInfo) is a an itanium target.
   MangleContext *createDeviceMangleContext(const TargetInfo &T);
 
   void DeepCollectObjCIvars(const ObjCInterfaceDecl *OI, bool leafClass,
                             SmallVectorImpl<const ObjCIvarDecl*> &Ivars) const;
 
   unsigned CountNonClassIvars(const ObjCInterfaceDecl *OI) const;
   void CollectInheritedProtocols(const Decl *CDecl,
                           llvm::SmallPtrSet<ObjCProtocolDecl*, 8> &Protocols);
 
   /// Return true if the specified type has unique object representations
   /// according to (C++17 [meta.unary.prop]p9)
   bool
   hasUniqueObjectRepresentations(QualType Ty,
                                  bool CheckIfTriviallyCopyable = true) const;
 
   //===--------------------------------------------------------------------===//
   //                            Type Operators
   //===--------------------------------------------------------------------===//
 
   /// Return the canonical (structural) type corresponding to the
   /// specified potentially non-canonical type \p T.
   ///
   /// The non-canonical version of a type may have many "decorated" versions of
   /// types.  Decorators can include typedefs, 'typeof' operators, etc. The
   /// returned type is guaranteed to be free of any of these, allowing two
   /// canonical types to be compared for exact equality with a simple pointer
   /// comparison.
   CanQualType getCanonicalType(QualType T) const {
     return CanQualType::CreateUnsafe(T.getCanonicalType());
   }
 
   const Type *getCanonicalType(const Type *T) const {
     return T->getCanonicalTypeInternal().getTypePtr();
   }
 
   /// Return the canonical parameter type corresponding to the specific
   /// potentially non-canonical one.
   ///
   /// Qualifiers are stripped off, functions are turned into function
   /// pointers, and arrays decay one level into pointers.
   CanQualType getCanonicalParamType(QualType T) const;
 
   /// Determine whether the given types \p T1 and \p T2 are equivalent.
   bool hasSameType(QualType T1, QualType T2) const {
     return getCanonicalType(T1) == getCanonicalType(T2);
   }
   bool hasSameType(const Type *T1, const Type *T2) const {
     return getCanonicalType(T1) == getCanonicalType(T2);
   }
 
   /// Determine whether the given expressions \p X and \p Y are equivalent.
   bool hasSameExpr(const Expr *X, const Expr *Y) const;
 
   /// Return this type as a completely-unqualified array type,
   /// capturing the qualifiers in \p Quals.
   ///
   /// This will remove the minimal amount of sugaring from the types, similar
   /// to the behavior of QualType::getUnqualifiedType().
   ///
   /// \param T is the qualified type, which may be an ArrayType
   ///
   /// \param Quals will receive the full set of qualifiers that were
   /// applied to the array.
   ///
   /// \returns if this is an array type, the completely unqualified array type
   /// that corresponds to it. Otherwise, returns T.getUnqualifiedType().
   QualType getUnqualifiedArrayType(QualType T, Qualifiers &Quals) const;
   QualType getUnqualifiedArrayType(QualType T) const {
     Qualifiers Quals;
     return getUnqualifiedArrayType(T, Quals);
   }
 
   /// Determine whether the given types are equivalent after
   /// cvr-qualifiers have been removed.
   bool hasSameUnqualifiedType(QualType T1, QualType T2) const {
     return getCanonicalType(T1).getTypePtr() ==
            getCanonicalType(T2).getTypePtr();
   }
 
   bool hasSameNullabilityTypeQualifier(QualType SubT, QualType SuperT,
                                        bool IsParam) const {
     auto SubTnullability = SubT->getNullability();
     auto SuperTnullability = SuperT->getNullability();
     if (SubTnullability.has_value() == SuperTnullability.has_value()) {
       // Neither has nullability; return true
       if (!SubTnullability)
         return true;
       // Both have nullability qualifier.
       if (*SubTnullability == *SuperTnullability ||
           *SubTnullability == NullabilityKind::Unspecified ||
           *SuperTnullability == NullabilityKind::Unspecified)
         return true;
 
       if (IsParam) {
         // Ok for the superclass method parameter to be "nonnull" and the subclass
         // method parameter to be "nullable"
         return (*SuperTnullability == NullabilityKind::NonNull &&
                 *SubTnullability == NullabilityKind::Nullable);
       }
       // For the return type, it's okay for the superclass method to specify
       // "nullable" and the subclass method specify "nonnull"
       return (*SuperTnullability == NullabilityKind::Nullable &&
               *SubTnullability == NullabilityKind::NonNull);
     }
     return true;
   }
 
   bool ObjCMethodsAreEqual(const ObjCMethodDecl *MethodDecl,
                            const ObjCMethodDecl *MethodImp);
 
   bool UnwrapSimilarTypes(QualType &T1, QualType &T2,
                           bool AllowPiMismatch = true) const;
   void UnwrapSimilarArrayTypes(QualType &T1, QualType &T2,
                                bool AllowPiMismatch = true) const;
 
   /// Determine if two types are similar, according to the C++ rules. That is,
   /// determine if they are the same other than qualifiers on the initial
   /// sequence of pointer / pointer-to-member / array (and in Clang, object
   /// pointer) types and their element types.
   ///
   /// Clang offers a number of qualifiers in addition to the C++ qualifiers;
   /// those qualifiers are also ignored in the 'similarity' check.
   bool hasSimilarType(QualType T1, QualType T2) const;
 
   /// Determine if two types are similar, ignoring only CVR qualifiers.
   bool hasCvrSimilarType(QualType T1, QualType T2);
 
   /// Retrieves the "canonical" nested name specifier for a
   /// given nested name specifier.
   ///
   /// The canonical nested name specifier is a nested name specifier
   /// that uniquely identifies a type or namespace within the type
   /// system. For example, given:
   ///
   /// \code
   /// namespace N {
   ///   struct S {
   ///     template<typename T> struct X { typename T* type; };
   ///   };
   /// }
   ///
   /// template<typename T> struct Y {
   ///   typename N::S::X<T>::type member;
   /// };
   /// \endcode
   ///
   /// Here, the nested-name-specifier for N::S::X<T>:: will be
   /// S::X<template-param-0-0>, since 'S' and 'X' are uniquely defined
   /// by declarations in the type system and the canonical type for
   /// the template type parameter 'T' is template-param-0-0.
   NestedNameSpecifier *
   getCanonicalNestedNameSpecifier(NestedNameSpecifier *NNS) const;
 
   /// Retrieves the default calling convention for the current target.
   CallingConv getDefaultCallingConvention(bool IsVariadic,
                                           bool IsCXXMethod,
                                           bool IsBuiltin = false) const;
 
   /// Retrieves the "canonical" template name that refers to a
   /// given template.
   ///
   /// The canonical template name is the simplest expression that can
   /// be used to refer to a given template. For most templates, this
   /// expression is just the template declaration itself. For example,
   /// the template std::vector can be referred to via a variety of
   /// names---std::vector, \::std::vector, vector (if vector is in
   /// scope), etc.---but all of these names map down to the same
   /// TemplateDecl, which is used to form the canonical template name.
   ///
   /// Dependent template names are more interesting. Here, the
   /// template name could be something like T::template apply or
   /// std::allocator<T>::template rebind, where the nested name
   /// specifier itself is dependent. In this case, the canonical
   /// template name uses the shortest form of the dependent
   /// nested-name-specifier, which itself contains all canonical
   /// types, values, and templates.
   TemplateName getCanonicalTemplateName(TemplateName Name,
                                         bool IgnoreDeduced = false) const;
 
   /// Determine whether the given template names refer to the same
   /// template.
   bool hasSameTemplateName(const TemplateName &X, const TemplateName &Y,
                            bool IgnoreDeduced = false) const;
 
   /// Determine whether the two declarations refer to the same entity.
   bool isSameEntity(const NamedDecl *X, const NamedDecl *Y) const;
 
   /// Determine whether two template parameter lists are similar enough
   /// that they may be used in declarations of the same template.
   bool isSameTemplateParameterList(const TemplateParameterList *X,
                                    const TemplateParameterList *Y) const;
 
   /// Determine whether two template parameters are similar enough
   /// that they may be used in declarations of the same template.
   bool isSameTemplateParameter(const NamedDecl *X, const NamedDecl *Y) const;
 
   /// Determine whether two 'requires' expressions are similar enough that they
   /// may be used in re-declarations.
   ///
   /// Use of 'requires' isn't mandatory, works with constraints expressed in
   /// other ways too.
   bool isSameConstraintExpr(const Expr *XCE, const Expr *YCE) const;
 
   /// Determine whether two type contraint are similar enough that they could
   /// used in declarations of the same template.
   bool isSameTypeConstraint(const TypeConstraint *XTC,
                             const TypeConstraint *YTC) const;
 
   /// Determine whether two default template arguments are similar enough
   /// that they may be used in declarations of the same template.
   bool isSameDefaultTemplateArgument(const NamedDecl *X,
                                      const NamedDecl *Y) const;
 
   /// Retrieve the "canonical" template argument.
   ///
   /// The canonical template argument is the simplest template argument
   /// (which may be a type, value, expression, or declaration) that
   /// expresses the value of the argument.
   TemplateArgument getCanonicalTemplateArgument(const TemplateArgument &Arg)
     const;
 
   /// Type Query functions.  If the type is an instance of the specified class,
   /// return the Type pointer for the underlying maximally pretty type.  This
   /// is a member of ASTContext because this may need to do some amount of
   /// canonicalization, e.g. to move type qualifiers into the element type.
   const ArrayType *getAsArrayType(QualType T) const;
   const ConstantArrayType *getAsConstantArrayType(QualType T) const {
     return dyn_cast_or_null<ConstantArrayType>(getAsArrayType(T));
   }
   const VariableArrayType *getAsVariableArrayType(QualType T) const {
     return dyn_cast_or_null<VariableArrayType>(getAsArrayType(T));
   }
   const IncompleteArrayType *getAsIncompleteArrayType(QualType T) const {
     return dyn_cast_or_null<IncompleteArrayType>(getAsArrayType(T));
   }
   const DependentSizedArrayType *getAsDependentSizedArrayType(QualType T)
     const {
     return dyn_cast_or_null<DependentSizedArrayType>(getAsArrayType(T));
   }
 
   /// Return the innermost element type of an array type.
   ///
   /// For example, will return "int" for int[m][n]
   QualType getBaseElementType(const ArrayType *VAT) const;
 
   /// Return the innermost element type of a type (which needn't
   /// actually be an array type).
   QualType getBaseElementType(QualType QT) const;
 
   /// Return number of constant array elements.
   uint64_t getConstantArrayElementCount(const ConstantArrayType *CA) const;
 
   /// Return number of elements initialized in an ArrayInitLoopExpr.
   uint64_t
   getArrayInitLoopExprElementCount(const ArrayInitLoopExpr *AILE) const;
 
   /// Perform adjustment on the parameter type of a function.
   ///
   /// This routine adjusts the given parameter type @p T to the actual
   /// parameter type used by semantic analysis (C99 6.7.5.3p[7,8],
   /// C++ [dcl.fct]p3). The adjusted parameter type is returned.
   QualType getAdjustedParameterType(QualType T) const;
 
   /// Retrieve the parameter type as adjusted for use in the signature
   /// of a function, decaying array and function types and removing top-level
   /// cv-qualifiers.
   QualType getSignatureParameterType(QualType T) const;
 
   QualType getExceptionObjectType(QualType T) const;
 
   /// Return the properly qualified result of decaying the specified
   /// array type to a pointer.
   ///
   /// This operation is non-trivial when handling typedefs etc.  The canonical
   /// type of \p T must be an array type, this returns a pointer to a properly
   /// qualified element of the array.
   ///
   /// See C99 6.7.5.3p7 and C99 6.3.2.1p3.
   QualType getArrayDecayedType(QualType T) const;
 
   /// Return the type that \p PromotableType will promote to: C99
   /// 6.3.1.1p2, assuming that \p PromotableType is a promotable integer type.
   QualType getPromotedIntegerType(QualType PromotableType) const;
 
   /// Recurses in pointer/array types until it finds an Objective-C
   /// retainable type and returns its ownership.
   Qualifiers::ObjCLifetime getInnerObjCOwnership(QualType T) const;
 
   /// Whether this is a promotable bitfield reference according
   /// to C99 6.3.1.1p2, bullet 2 (and GCC extensions).
   ///
   /// \returns the type this bit-field will promote to, or NULL if no
   /// promotion occurs.
   QualType isPromotableBitField(Expr *E) const;
 
   /// Return the highest ranked integer type, see C99 6.3.1.8p1.
   ///
   /// If \p LHS > \p RHS, returns 1.  If \p LHS == \p RHS, returns 0.  If
   /// \p LHS < \p RHS, return -1.
   int getIntegerTypeOrder(QualType LHS, QualType RHS) const;
 
   /// Compare the rank of the two specified floating point types,
   /// ignoring the domain of the type (i.e. 'double' == '_Complex double').
   ///
   /// If \p LHS > \p RHS, returns 1.  If \p LHS == \p RHS, returns 0.  If
   /// \p LHS < \p RHS, return -1.
   int getFloatingTypeOrder(QualType LHS, QualType RHS) const;
 
   /// Compare the rank of two floating point types as above, but compare equal
   /// if both types have the same floating-point semantics on the target (i.e.
   /// long double and double on AArch64 will return 0).
   int getFloatingTypeSemanticOrder(QualType LHS, QualType RHS) const;
 
   unsigned getTargetAddressSpace(LangAS AS) const;
 
   LangAS getLangASForBuiltinAddressSpace(unsigned AS) const;
 
   /// Get target-dependent integer value for null pointer which is used for
   /// constant folding.
   uint64_t getTargetNullPointerValue(QualType QT) const;
 
   bool addressSpaceMapManglingFor(LangAS AS) const {
     return AddrSpaceMapMangling || isTargetAddressSpace(AS);
   }
 
   bool hasAnyFunctionEffects() const { return AnyFunctionEffects; }
 
   // Merges two exception specifications, such that the resulting
   // exception spec is the union of both. For example, if either
   // of them can throw something, the result can throw it as well.
   FunctionProtoType::ExceptionSpecInfo
   mergeExceptionSpecs(FunctionProtoType::ExceptionSpecInfo ESI1,
                       FunctionProtoType::ExceptionSpecInfo ESI2,
                       SmallVectorImpl<QualType> &ExceptionTypeStorage,
                       bool AcceptDependent);
 
   // For two "same" types, return a type which has
   // the common sugar between them. If Unqualified is true,
   // both types need only be the same unqualified type.
   // The result will drop the qualifiers which do not occur
   // in both types.
   QualType getCommonSugaredType(QualType X, QualType Y,
                                 bool Unqualified = false);
 
 private:
   // Helper for integer ordering
   unsigned getIntegerRank(const Type *T) const;
 
 public:
   //===--------------------------------------------------------------------===//
   //                    Type Compatibility Predicates
   //===--------------------------------------------------------------------===//
 
   /// Compatibility predicates used to check assignment expressions.
   bool typesAreCompatible(QualType T1, QualType T2,
                           bool CompareUnqualified = false); // C99 6.2.7p1
 
   bool propertyTypesAreCompatible(QualType, QualType);
   bool typesAreBlockPointerCompatible(QualType, QualType);
 
   bool isObjCIdType(QualType T) const {
     if (const auto *ET = dyn_cast<ElaboratedType>(T))
       T = ET->getNamedType();
     return T == getObjCIdType();
   }
 
   bool isObjCClassType(QualType T) const {
     if (const auto *ET = dyn_cast<ElaboratedType>(T))
       T = ET->getNamedType();
     return T == getObjCClassType();
   }
 
   bool isObjCSelType(QualType T) const {
     if (const auto *ET = dyn_cast<ElaboratedType>(T))
       T = ET->getNamedType();
     return T == getObjCSelType();
   }
 
   bool ObjCQualifiedIdTypesAreCompatible(const ObjCObjectPointerType *LHS,
                                          const ObjCObjectPointerType *RHS,
                                          bool ForCompare);
 
   bool ObjCQualifiedClassTypesAreCompatible(const ObjCObjectPointerType *LHS,
                                             const ObjCObjectPointerType *RHS);
 
   // Check the safety of assignment from LHS to RHS
   bool canAssignObjCInterfaces(const ObjCObjectPointerType *LHSOPT,
                                const ObjCObjectPointerType *RHSOPT);
   bool canAssignObjCInterfaces(const ObjCObjectType *LHS,
                                const ObjCObjectType *RHS);
   bool canAssignObjCInterfacesInBlockPointer(
                                           const ObjCObjectPointerType *LHSOPT,
                                           const ObjCObjectPointerType *RHSOPT,
                                           bool BlockReturnType);
   bool areComparableObjCPointerTypes(QualType LHS, QualType RHS);
   QualType areCommonBaseCompatible(const ObjCObjectPointerType *LHSOPT,
                                    const ObjCObjectPointerType *RHSOPT);
   bool canBindObjCObjectType(QualType To, QualType From);
 
   // Functions for calculating composite types
   QualType mergeTypes(QualType, QualType, bool OfBlockPointer = false,
                       bool Unqualified = false, bool BlockReturnType = false,
                       bool IsConditionalOperator = false);
   QualType mergeFunctionTypes(QualType, QualType, bool OfBlockPointer = false,
                               bool Unqualified = false, bool AllowCXX = false,
                               bool IsConditionalOperator = false);
   QualType mergeFunctionParameterTypes(QualType, QualType,
                                        bool OfBlockPointer = false,
                                        bool Unqualified = false);
   QualType mergeTransparentUnionType(QualType, QualType,
                                      bool OfBlockPointer=false,
                                      bool Unqualified = false);
 
   QualType mergeObjCGCQualifiers(QualType, QualType);
 
   /// This function merges the ExtParameterInfo lists of two functions. It
   /// returns true if the lists are compatible. The merged list is returned in
   /// NewParamInfos.
   ///
   /// \param FirstFnType The type of the first function.
   ///
   /// \param SecondFnType The type of the second function.
   ///
   /// \param CanUseFirst This flag is set to true if the first function's
   /// ExtParameterInfo list can be used as the composite list of
   /// ExtParameterInfo.
   ///
   /// \param CanUseSecond This flag is set to true if the second function's
   /// ExtParameterInfo list can be used as the composite list of
   /// ExtParameterInfo.
   ///
   /// \param NewParamInfos The composite list of ExtParameterInfo. The list is
   /// empty if none of the flags are set.
   ///
   bool mergeExtParameterInfo(
       const FunctionProtoType *FirstFnType,
       const FunctionProtoType *SecondFnType,
       bool &CanUseFirst, bool &CanUseSecond,
       SmallVectorImpl<FunctionProtoType::ExtParameterInfo> &NewParamInfos);
 
   void ResetObjCLayout(const ObjCContainerDecl *CD);
 
   //===--------------------------------------------------------------------===//
   //                    Integer Predicates
   //===--------------------------------------------------------------------===//
 
   // The width of an integer, as defined in C99 6.2.6.2. This is the number
   // of bits in an integer type excluding any padding bits.
   unsigned getIntWidth(QualType T) const;
 
   // Per C99 6.2.5p6, for every signed integer type, there is a corresponding
   // unsigned integer type.  This method takes a signed type, and returns the
   // corresponding unsigned integer type.
   // With the introduction of fixed point types in ISO N1169, this method also
   // accepts fixed point types and returns the corresponding unsigned type for
   // a given fixed point type.
   QualType getCorrespondingUnsignedType(QualType T) const;
 
   // Per C99 6.2.5p6, for every signed integer type, there is a corresponding
   // unsigned integer type.  This method takes an unsigned type, and returns the
   // corresponding signed integer type.
   // With the introduction of fixed point types in ISO N1169, this method also
   // accepts fixed point types and returns the corresponding signed type for
   // a given fixed point type.
   QualType getCorrespondingSignedType(QualType T) const;
 
   // Per ISO N1169, this method accepts fixed point types and returns the
   // corresponding saturated type for a given fixed point type.
   QualType getCorrespondingSaturatedType(QualType Ty) const;
 
   // Per ISO N1169, this method accepts fixed point types and returns the
   // corresponding non-saturated type for a given fixed point type.
   QualType getCorrespondingUnsaturatedType(QualType Ty) const;
 
   // This method accepts fixed point types and returns the corresponding signed
   // type. Unlike getCorrespondingUnsignedType(), this only accepts unsigned
   // fixed point types because there are unsigned integer types like bool and
   // char8_t that don't have signed equivalents.
   QualType getCorrespondingSignedFixedPointType(QualType Ty) const;
 
   //===--------------------------------------------------------------------===//
   //                    Integer Values
   //===--------------------------------------------------------------------===//
 
   /// Make an APSInt of the appropriate width and signedness for the
   /// given \p Value and integer \p Type.
   llvm::APSInt MakeIntValue(uint64_t Value, QualType Type) const {
     // If Type is a signed integer type larger than 64 bits, we need to be sure
     // to sign extend Res appropriately.
     llvm::APSInt Res(64, !Type->isSignedIntegerOrEnumerationType());
     Res = Value;
     unsigned Width = getIntWidth(Type);
     if (Width != Res.getBitWidth())
       return Res.extOrTrunc(Width);
     return Res;
   }
 
   bool isSentinelNullExpr(const Expr *E);
 
   /// Get the implementation of the ObjCInterfaceDecl \p D, or nullptr if
   /// none exists.
   ObjCImplementationDecl *getObjCImplementation(ObjCInterfaceDecl *D);
 
   /// Get the implementation of the ObjCCategoryDecl \p D, or nullptr if
   /// none exists.
   ObjCCategoryImplDecl *getObjCImplementation(ObjCCategoryDecl *D);
 
   /// Return true if there is at least one \@implementation in the TU.
   bool AnyObjCImplementation() {
     return !ObjCImpls.empty();
   }
 
   /// Set the implementation of ObjCInterfaceDecl.
   void setObjCImplementation(ObjCInterfaceDecl *IFaceD,
                              ObjCImplementationDecl *ImplD);
 
   /// Set the implementation of ObjCCategoryDecl.
   void setObjCImplementation(ObjCCategoryDecl *CatD,
                              ObjCCategoryImplDecl *ImplD);
 
   /// Get the duplicate declaration of a ObjCMethod in the same
   /// interface, or null if none exists.
   const ObjCMethodDecl *
   getObjCMethodRedeclaration(const ObjCMethodDecl *MD) const;
 
   void setObjCMethodRedeclaration(const ObjCMethodDecl *MD,
                                   const ObjCMethodDecl *Redecl);
 
   /// Returns the Objective-C interface that \p ND belongs to if it is
   /// an Objective-C method/property/ivar etc. that is part of an interface,
   /// otherwise returns null.
   const ObjCInterfaceDecl *getObjContainingInterface(const NamedDecl *ND) const;
 
   /// Set the copy initialization expression of a block var decl. \p CanThrow
   /// indicates whether the copy expression can throw or not.
   void setBlockVarCopyInit(const VarDecl* VD, Expr *CopyExpr, bool CanThrow);
 
   /// Get the copy initialization expression of the VarDecl \p VD, or
   /// nullptr if none exists.
   BlockVarCopyInit getBlockVarCopyInit(const VarDecl* VD) const;
 
   /// Allocate an uninitialized TypeSourceInfo.
   ///
   /// The caller should initialize the memory held by TypeSourceInfo using
   /// the TypeLoc wrappers.
   ///
   /// \param T the type that will be the basis for type source info. This type
   /// should refer to how the declarator was written in source code, not to
   /// what type semantic analysis resolved the declarator to.
   ///
   /// \param Size the size of the type info to create, or 0 if the size
   /// should be calculated based on the type.
   TypeSourceInfo *CreateTypeSourceInfo(QualType T, unsigned Size = 0) const;
 
   /// Allocate a TypeSourceInfo where all locations have been
   /// initialized to a given location, which defaults to the empty
   /// location.
   TypeSourceInfo *
   getTrivialTypeSourceInfo(QualType T,
                            SourceLocation Loc = SourceLocation()) const;
 
   /// Add a deallocation callback that will be invoked when the
   /// ASTContext is destroyed.
   ///
   /// \param Callback A callback function that will be invoked on destruction.
   ///
   /// \param Data Pointer data that will be provided to the callback function
   /// when it is called.
   void AddDeallocation(void (*Callback)(void *), void *Data) const;
 
   /// If T isn't trivially destructible, calls AddDeallocation to register it
   /// for destruction.
   template <typename T> void addDestruction(T *Ptr) const {
     if (!std::is_trivially_destructible<T>::value) {
       auto DestroyPtr = [](void *V) { static_cast<T *>(V)->~T(); };
       AddDeallocation(DestroyPtr, Ptr);
     }
   }
 
   GVALinkage GetGVALinkageForFunction(const FunctionDecl *FD) const;
   GVALinkage GetGVALinkageForVariable(const VarDecl *VD) const;
 
   /// Determines if the decl can be CodeGen'ed or deserialized from PCH
   /// lazily, only when used; this is only relevant for function or file scoped
   /// var definitions.
   ///
   /// \returns true if the function/var must be CodeGen'ed/deserialized even if
   /// it is not used.
   bool DeclMustBeEmitted(const Decl *D);
 
   /// Visits all versions of a multiversioned function with the passed
   /// predicate.
   void forEachMultiversionedFunctionVersion(
       const FunctionDecl *FD,
       llvm::function_ref<void(FunctionDecl *)> Pred) const;
 
   const CXXConstructorDecl *
   getCopyConstructorForExceptionObject(CXXRecordDecl *RD);
 
   void addCopyConstructorForExceptionObject(CXXRecordDecl *RD,
                                             CXXConstructorDecl *CD);
 
   void addTypedefNameForUnnamedTagDecl(TagDecl *TD, TypedefNameDecl *TND);
 
   TypedefNameDecl *getTypedefNameForUnnamedTagDecl(const TagDecl *TD);
 
   void addDeclaratorForUnnamedTagDecl(TagDecl *TD, DeclaratorDecl *DD);
 
   DeclaratorDecl *getDeclaratorForUnnamedTagDecl(const TagDecl *TD);
 
   void setManglingNumber(const NamedDecl *ND, unsigned Number);
   unsigned getManglingNumber(const NamedDecl *ND,
                              bool ForAuxTarget = false) const;
 
   void setStaticLocalNumber(const VarDecl *VD, unsigned Number);
   unsigned getStaticLocalNumber(const VarDecl *VD) const;
 
   /// Retrieve the context for computing mangling numbers in the given
   /// DeclContext.
   MangleNumberingContext &getManglingNumberContext(const DeclContext *DC);
   enum NeedExtraManglingDecl_t { NeedExtraManglingDecl };
   MangleNumberingContext &getManglingNumberContext(NeedExtraManglingDecl_t,
                                                    const Decl *D);
 
   std::unique_ptr<MangleNumberingContext> createMangleNumberingContext() const;
 
   /// Used by ParmVarDecl to store on the side the
   /// index of the parameter when it exceeds the size of the normal bitfield.
   void setParameterIndex(const ParmVarDecl *D, unsigned index);
 
   /// Used by ParmVarDecl to retrieve on the side the
   /// index of the parameter when it exceeds the size of the normal bitfield.
   unsigned getParameterIndex(const ParmVarDecl *D) const;
 
   /// Return a string representing the human readable name for the specified
   /// function declaration or file name. Used by SourceLocExpr and
   /// PredefinedExpr to cache evaluated results.
   StringLiteral *getPredefinedStringLiteralFromCache(StringRef Key) const;
 
   /// Return the next version number to be used for a string literal evaluated
   /// as part of constant evaluation.
   unsigned getNextStringLiteralVersion() { return NextStringLiteralVersion++; }
 
   /// Return a declaration for the global GUID object representing the given
   /// GUID value.
   MSGuidDecl *getMSGuidDecl(MSGuidDeclParts Parts) const;
 
   /// Return a declaration for a uniquified anonymous global constant
   /// corresponding to a given APValue.
   UnnamedGlobalConstantDecl *
   getUnnamedGlobalConstantDecl(QualType Ty, const APValue &Value) const;
 
   /// Return the template parameter object of the given type with the given
   /// value.
   TemplateParamObjectDecl *getTemplateParamObjectDecl(QualType T,
                                                       const APValue &V) const;
 
   /// Parses the target attributes passed in, and returns only the ones that are
   /// valid feature names.
   ParsedTargetAttr filterFunctionTargetAttrs(const TargetAttr *TD) const;
 
   void getFunctionFeatureMap(llvm::StringMap<bool> &FeatureMap,
                              const FunctionDecl *) const;
   void getFunctionFeatureMap(llvm::StringMap<bool> &FeatureMap,
                              GlobalDecl GD) const;
 
   /// Generates and stores SYCL kernel metadata for the provided
   /// SYCL kernel entry point function. The provided function must have
   /// an attached sycl_kernel_entry_point attribute that specifies a unique
   /// type for the name of a SYCL kernel. Callers are required to detect
   /// conflicting SYCL kernel names and issue a diagnostic prior to calling
   /// this function.
   void registerSYCLEntryPointFunction(FunctionDecl *FD);
 
   /// Given a type used as a SYCL kernel name, returns a reference to the
   /// metadata generated from the corresponding SYCL kernel entry point.
   /// Aborts if the provided type is not a registered SYCL kernel name.
   const SYCLKernelInfo &getSYCLKernelInfo(QualType T) const;
 
   /// Returns a pointer to the metadata generated from the corresponding
   /// SYCLkernel entry point if the provided type corresponds to a registered
   /// SYCL kernel name. Returns a null pointer otherwise.
   const SYCLKernelInfo *findSYCLKernelInfo(QualType T) const;
 
   //===--------------------------------------------------------------------===//
   //                    Statistics
   //===--------------------------------------------------------------------===//
 
   /// The number of implicitly-declared default constructors.
   unsigned NumImplicitDefaultConstructors = 0;
 
   /// The number of implicitly-declared default constructors for
   /// which declarations were built.
   unsigned NumImplicitDefaultConstructorsDeclared = 0;
 
   /// The number of implicitly-declared copy constructors.
   unsigned NumImplicitCopyConstructors = 0;
 
   /// The number of implicitly-declared copy constructors for
   /// which declarations were built.
   unsigned NumImplicitCopyConstructorsDeclared = 0;
 
   /// The number of implicitly-declared move constructors.
   unsigned NumImplicitMoveConstructors = 0;
 
   /// The number of implicitly-declared move constructors for
   /// which declarations were built.
   unsigned NumImplicitMoveConstructorsDeclared = 0;
 
   /// The number of implicitly-declared copy assignment operators.
   unsigned NumImplicitCopyAssignmentOperators = 0;
 
   /// The number of implicitly-declared copy assignment operators for
   /// which declarations were built.
   unsigned NumImplicitCopyAssignmentOperatorsDeclared = 0;
 
   /// The number of implicitly-declared move assignment operators.
   unsigned NumImplicitMoveAssignmentOperators = 0;
 
   /// The number of implicitly-declared move assignment operators for
   /// which declarations were built.
   unsigned NumImplicitMoveAssignmentOperatorsDeclared = 0;
 
   /// The number of implicitly-declared destructors.
   unsigned NumImplicitDestructors = 0;
 
   /// The number of implicitly-declared destructors for which
   /// declarations were built.
   unsigned NumImplicitDestructorsDeclared = 0;
 
 public:
   /// Initialize built-in types.
   ///
   /// This routine may only be invoked once for a given ASTContext object.
   /// It is normally invoked after ASTContext construction.
   ///
   /// \param Target The target
   void InitBuiltinTypes(const TargetInfo &Target,
                         const TargetInfo *AuxTarget = nullptr);
 
 private:
   void InitBuiltinType(CanQualType &R, BuiltinType::Kind K);
 
   class ObjCEncOptions {
     unsigned Bits;
 
     ObjCEncOptions(unsigned Bits) : Bits(Bits) {}
 
   public:
     ObjCEncOptions() : Bits(0) {}
 
 #define OPT_LIST(V)                                                            \
   V(ExpandPointedToStructures, 0)                                              \
   V(ExpandStructures, 1)                                                       \
   V(IsOutermostType, 2)                                                        \
   V(EncodingProperty, 3)                                                       \
   V(IsStructField, 4)                                                          \
   V(EncodeBlockParameters, 5)                                                  \
   V(EncodeClassNames, 6)                                                       \
 
 #define V(N,I) ObjCEncOptions& set##N() { Bits |= 1 << I; return *this; }
 OPT_LIST(V)
 #undef V
 
 #define V(N,I) bool N() const { return Bits & 1 << I; }
 OPT_LIST(V)
 #undef V
 
 #undef OPT_LIST
 
     [[nodiscard]] ObjCEncOptions keepingOnly(ObjCEncOptions Mask) const {
       return Bits & Mask.Bits;
     }
 
     [[nodiscard]] ObjCEncOptions forComponentType() const {
       ObjCEncOptions Mask = ObjCEncOptions()
                                 .setIsOutermostType()
                                 .setIsStructField();
       return Bits & ~Mask.Bits;
     }
   };
 
   // Return the Objective-C type encoding for a given type.
   void getObjCEncodingForTypeImpl(QualType t, std::string &S,
                                   ObjCEncOptions Options,
                                   const FieldDecl *Field,
                                   QualType *NotEncodedT = nullptr) const;
 
   // Adds the encoding of the structure's members.
   void getObjCEncodingForStructureImpl(RecordDecl *RD, std::string &S,
                                        const FieldDecl *Field,
                                        bool includeVBases = true,
                                        QualType *NotEncodedT=nullptr) const;
 
 public:
   // Adds the encoding of a method parameter or return type.
   void getObjCEncodingForMethodParameter(Decl::ObjCDeclQualifier QT,
                                          QualType T, std::string& S,
                                          bool Extended) const;
 
   /// Returns true if this is an inline-initialized static data member
   /// which is treated as a definition for MSVC compatibility.
   bool isMSStaticDataMemberInlineDefinition(const VarDecl *VD) const;
 
   enum class InlineVariableDefinitionKind {
     /// Not an inline variable.
     None,
 
     /// Weak definition of inline variable.
     Weak,
 
     /// Weak for now, might become strong later in this TU.
     WeakUnknown,
 
     /// Strong definition.
     Strong
   };
 
   /// Determine whether a definition of this inline variable should
   /// be treated as a weak or strong definition. For compatibility with
   /// C++14 and before, for a constexpr static data member, if there is an
   /// out-of-line declaration of the member, we may promote it from weak to
   /// strong.
   InlineVariableDefinitionKind
   getInlineVariableDefinitionKind(const VarDecl *VD) const;
 
 private:
   friend class DeclarationNameTable;
   friend class DeclContext;
 
   const ASTRecordLayout &
   getObjCLayout(const ObjCInterfaceDecl *D,
                 const ObjCImplementationDecl *Impl) const;
 
   /// A set of deallocations that should be performed when the
   /// ASTContext is destroyed.
   // FIXME: We really should have a better mechanism in the ASTContext to
   // manage running destructors for types which do variable sized allocation
   // within the AST. In some places we thread the AST bump pointer allocator
   // into the datastructures which avoids this mess during deallocation but is
   // wasteful of memory, and here we require a lot of error prone book keeping
   // in order to track and run destructors while we're tearing things down.
   using DeallocationFunctionsAndArguments =
       llvm::SmallVector<std::pair<void (*)(void *), void *>, 16>;
   mutable DeallocationFunctionsAndArguments Deallocations;
 
   // FIXME: This currently contains the set of StoredDeclMaps used
   // by DeclContext objects.  This probably should not be in ASTContext,
   // but we include it here so that ASTContext can quickly deallocate them.
   llvm::PointerIntPair<StoredDeclsMap *, 1> LastSDM;
 
   std::vector<Decl *> TraversalScope;
 
   std::unique_ptr<VTableContextBase> VTContext;
 
   void ReleaseDeclContextMaps();
 
 public:
   enum PragmaSectionFlag : unsigned {
     PSF_None = 0,
     PSF_Read = 0x1,
     PSF_Write = 0x2,
     PSF_Execute = 0x4,
     PSF_Implicit = 0x8,
     PSF_ZeroInit = 0x10,
     PSF_Invalid = 0x80000000U,
   };
 
   struct SectionInfo {
     NamedDecl *Decl;
     SourceLocation PragmaSectionLocation;
     int SectionFlags;
 
     SectionInfo() = default;
     SectionInfo(NamedDecl *Decl, SourceLocation PragmaSectionLocation,
                 int SectionFlags)
         : Decl(Decl), PragmaSectionLocation(PragmaSectionLocation),
           SectionFlags(SectionFlags) {}
   };
 
   llvm::StringMap<SectionInfo> SectionInfos;
 
   /// Return a new OMPTraitInfo object owned by this context.
   OMPTraitInfo &getNewOMPTraitInfo();
 
   /// Whether a C++ static variable or CUDA/HIP kernel may be externalized.
   bool mayExternalize(const Decl *D) const;
 
   /// Whether a C++ static variable or CUDA/HIP kernel should be externalized.
   bool shouldExternalize(const Decl *D) const;
 
   /// Resolve the root record to be used to derive the vtable pointer
   /// authentication policy for the specified record.
   const CXXRecordDecl *
   baseForVTableAuthentication(const CXXRecordDecl *ThisClass);
   bool useAbbreviatedThunkName(GlobalDecl VirtualMethodDecl,
                                StringRef MangledName);
 
   StringRef getCUIDHash() const;
 
 private:
   /// All OMPTraitInfo objects live in this collection, one per
   /// `pragma omp [begin] declare variant` directive.
   SmallVector<std::unique_ptr<OMPTraitInfo>, 4> OMPTraitInfoVector;
 
   llvm::DenseMap<GlobalDecl, llvm::StringSet<>> ThunksToBeAbbreviated;
 };
 
 /// Insertion operator for diagnostics.
 const StreamingDiagnostic &operator<<(const StreamingDiagnostic &DB,
                                       const ASTContext::SectionInfo &Section);
 
 /// Utility function for constructing a nullary selector.
 inline Selector GetNullarySelector(StringRef name, ASTContext &Ctx) {
   const IdentifierInfo *II = &Ctx.Idents.get(name);
   return Ctx.Selectors.getSelector(0, &II);
 }
 
 /// Utility function for constructing an unary selector.
 inline Selector GetUnarySelector(StringRef name, ASTContext &Ctx) {
   const IdentifierInfo *II = &Ctx.Idents.get(name);
   return Ctx.Selectors.getSelector(1, &II);
 }
 
 } // namespace clang
 
 // operator new and delete aren't allowed inside namespaces.
 
 /// Placement new for using the ASTContext's allocator.
 ///
 /// This placement form of operator new uses the ASTContext's allocator for
 /// obtaining memory.
 ///
 /// IMPORTANT: These are also declared in clang/AST/ASTContextAllocate.h!
 /// Any changes here need to also be made there.
 ///
 /// We intentionally avoid using a nothrow specification here so that the calls
 /// to this operator will not perform a null check on the result -- the
 /// underlying allocator never returns null pointers.
 ///
 /// Usage looks like this (assuming there's an ASTContext 'Context' in scope):
 /// @code
 /// // Default alignment (8)
 /// IntegerLiteral *Ex = new (Context) IntegerLiteral(arguments);
 /// // Specific alignment
 /// IntegerLiteral *Ex2 = new (Context, 4) IntegerLiteral(arguments);
 /// @endcode
 /// Memory allocated through this placement new operator does not need to be
 /// explicitly freed, as ASTContext will free all of this memory when it gets
 /// destroyed. Please note that you cannot use delete on the pointer.
 ///
 /// @param Bytes The number of bytes to allocate. Calculated by the compiler.
 /// @param C The ASTContext that provides the allocator.
 /// @param Alignment The alignment of the allocated memory (if the underlying
 ///                  allocator supports it).
 /// @return The allocated memory. Could be nullptr.
 inline void *operator new(size_t Bytes, const clang::ASTContext &C,
                           size_t Alignment /* = 8 */) {
   return C.Allocate(Bytes, Alignment);
 }
 
 /// Placement delete companion to the new above.
 ///
 /// This operator is just a companion to the new above. There is no way of
 /// invoking it directly; see the new operator for more details. This operator
 /// is called implicitly by the compiler if a placement new expression using
 /// the ASTContext throws in the object constructor.
 inline void operator delete(void *Ptr, const clang::ASTContext &C, size_t) {
   C.Deallocate(Ptr);
 }
 
 /// This placement form of operator new[] uses the ASTContext's allocator for
 /// obtaining memory.
 ///
 /// We intentionally avoid using a nothrow specification here so that the calls
 /// to this operator will not perform a null check on the result -- the
 /// underlying allocator never returns null pointers.
 ///
 /// Usage looks like this (assuming there's an ASTContext 'Context' in scope):
 /// @code
 /// // Default alignment (8)
 /// char *data = new (Context) char[10];
 /// // Specific alignment
 /// char *data = new (Context, 4) char[10];
 /// @endcode
 /// Memory allocated through this placement new[] operator does not need to be
 /// explicitly freed, as ASTContext will free all of this memory when it gets
 /// destroyed. Please note that you cannot use delete on the pointer.
 ///
 /// @param Bytes The number of bytes to allocate. Calculated by the compiler.
 /// @param C The ASTContext that provides the allocator.
 /// @param Alignment The alignment of the allocated memory (if the underlying
 ///                  allocator supports it).
 /// @return The allocated memory. Could be nullptr.
 inline void *operator new[](size_t Bytes, const clang::ASTContext& C,
                             size_t Alignment /* = 8 */) {
   return C.Allocate(Bytes, Alignment);
 }
 
 /// Placement delete[] companion to the new[] above.
 ///
 /// This operator is just a companion to the new[] above. There is no way of
 /// invoking it directly; see the new[] operator for more details. This operator
 /// is called implicitly by the compiler if a placement new[] expression using
 /// the ASTContext throws in the object constructor.
 inline void operator delete[](void *Ptr, const clang::ASTContext &C, size_t) {
   C.Deallocate(Ptr);
 }
 
 /// Create the representation of a LazyGenerationalUpdatePtr.
 template <typename Owner, typename T,
           void (clang::ExternalASTSource::*Update)(Owner)>
 typename clang::LazyGenerationalUpdatePtr<Owner, T, Update>::ValueType
     clang::LazyGenerationalUpdatePtr<Owner, T, Update>::makeValue(
         const clang::ASTContext &Ctx, T Value) {
   // Note, this is implemented here so that ExternalASTSource.h doesn't need to
   // include ASTContext.h. We explicitly instantiate it for all relevant types
   // in ASTContext.cpp.
   if (auto *Source = Ctx.getExternalSource())
     return new (Ctx) LazyData(Source, Value);
   return Value;
 }
 
 #endif // LLVM_CLANG_AST_ASTCONTEXT_H